Turn off AnimationControllers when not in use (#5902)

This requires all AnimationController objects to be given a
TickerProvider, a class that can create the Ticker.

It also provides some nice mixins for people who want to have their
State provide a TickerProvider. And a schedulerTickerProvider for those
cases where you just want to see your battery burn.

Also, we now enforce destruction order for elements.

examples/flutter_gallery/lib/demo/animation_demo.dart

@@ -393,11 +393,14 @@ class _RectangleDemoState extends State<_RectangleDemo> {
 typedef Widget _DemoBuilder(_ArcDemo demo);
 
 class _ArcDemo {
-  _ArcDemo(String _title, this.builder) : title = _title, key = new GlobalKey(debugLabel: _title);
+  _ArcDemo(String _title, this.builder, TickerProvider vsync)
+    : title = _title,
+      controller = new AnimationController(duration: const Duration(milliseconds: 500), vsync: vsync),
+      key = new GlobalKey(debugLabel: _title);
 
-  final AnimationController controller = new AnimationController(duration: const Duration(milliseconds: 500));
   final String title;
   final _DemoBuilder builder;
+  final AnimationController controller;
   final GlobalKey key;
 }
 
@@ -410,23 +413,29 @@ class AnimationDemo extends StatefulWidget {
   _AnimationDemoState createState() => new _AnimationDemoState();
 }
 
-class _AnimationDemoState extends State<AnimationDemo> {
+class _AnimationDemoState extends State<AnimationDemo> with TickerProviderStateMixin {
   static final GlobalKey<TabBarSelectionState<_ArcDemo>> _tabsKey = new GlobalKey<TabBarSelectionState<_ArcDemo>>();
 
-  static final List<_ArcDemo> _allDemos = <_ArcDemo>[
+  List<_ArcDemo> _allDemos;
-    new _ArcDemo('POINT', (_ArcDemo demo) {
+
-      return new _PointDemo(
+  @override
-        key: demo.key,
+  void initState() {
-        controller: demo.controller
+    super.initState();
-      );
+    _allDemos = <_ArcDemo>[
-    }),
+      new _ArcDemo('POINT', (_ArcDemo demo) {
-    new _ArcDemo('RECTANGLE', (_ArcDemo demo) {
+        return new _PointDemo(
-      return new _RectangleDemo(
+          key: demo.key,
-        key: demo.key,
+          controller: demo.controller
-        controller: demo.controller
+        );
-      );
+      }, this),
-    })
+      new _ArcDemo('RECTANGLE', (_ArcDemo demo) {
-  ];
+        return new _RectangleDemo(
+          key: demo.key,
+          controller: demo.controller
+        );
+      }, this),
+    ];
+  }
 
   Future<Null> _play() async {
     _ArcDemo demo = _tabsKey.currentState.value;

examples/flutter_gallery/lib/demo/bottom_navigation_demo.dart

@@ -8,7 +8,8 @@ class NavigationIconView {
   NavigationIconView({
     Icon icon,
     Widget title,
-    Color color
+    Color color,
+    TickerProvider vsync,
   }) : _icon = icon,
        _color = color,
        destinationLabel = new DestinationLabel(
@@ -17,13 +18,14 @@ class NavigationIconView {
          backgroundColor: color
        ),
        controller = new AnimationController(
-         duration: kThemeAnimationDuration
+         duration: kThemeAnimationDuration,
+         vsync: vsync,
        ) {
-         _animation = new CurvedAnimation(
+    _animation = new CurvedAnimation(
-           parent: controller,
+      parent: controller,
-           curve: new Interval(0.5, 1.0, curve: Curves.fastOutSlowIn)
+      curve: new Interval(0.5, 1.0, curve: Curves.fastOutSlowIn)
-         );
+    );
-       }
+  }
 
   final Icon _icon;
   final Color _color;
@@ -61,7 +63,7 @@ class BottomNavigationDemo extends StatefulWidget {
   _BottomNavigationDemoState createState() => new _BottomNavigationDemoState();
 }
 
-class _BottomNavigationDemoState extends State<BottomNavigationDemo> {
+class _BottomNavigationDemoState extends State<BottomNavigationDemo> with TickerProviderStateMixin {
   int _currentIndex = 0;
   BottomNavigationBarType _type = BottomNavigationBarType.shifting;
   List<NavigationIconView> _navigationViews;
@@ -73,22 +75,26 @@ class _BottomNavigationDemoState extends State<BottomNavigationDemo> {
       new NavigationIconView(
         icon: new Icon(Icons.access_alarm),
         title: new Text('Alarm'),
-        color: Colors.deepPurple[500]
+        color: Colors.deepPurple[500],
+        vsync: this,
       ),
       new NavigationIconView(
         icon: new Icon(Icons.cloud),
         title: new Text('Cloud'),
-        color: Colors.teal[500]
+        color: Colors.teal[500],
+        vsync: this,
       ),
       new NavigationIconView(
         icon: new Icon(Icons.favorite),
         title: new Text('Favorites'),
-        color: Colors.indigo[500]
+        color: Colors.indigo[500],
+        vsync: this,
       ),
       new NavigationIconView(
         icon: new Icon(Icons.event_available),
         title: new Text('Event'),
-        color: Colors.pink[500]
+        color: Colors.pink[500],
+        vsync: this,
       )
     ];
 
@@ -124,14 +130,12 @@ class _BottomNavigationDemoState extends State<BottomNavigationDemo> {
       return aValue.compareTo(bValue);
     });
 
-    return new Stack(
+    return new Stack(children: transitions);
-      children: transitions
-    );
   }
 
   @override
   Widget build(BuildContext context) {
-    BottomNavigationBar botNavBar = new BottomNavigationBar(
+    final BottomNavigationBar botNavBar = new BottomNavigationBar(
       labels: _navigationViews.map(
         (NavigationIconView navigationView) => navigationView.destinationLabel
       ).toList(),
@@ -159,18 +163,18 @@ class _BottomNavigationDemoState extends State<BottomNavigationDemo> {
             itemBuilder: (BuildContext context) => <PopupMenuItem<BottomNavigationBarType>>[
               new PopupMenuItem<BottomNavigationBarType>(
                 value: BottomNavigationBarType.fixed,
-                child: new Text('Fixed')
+                child: new Text('Fixed'),
               ),
               new PopupMenuItem<BottomNavigationBarType>(
                 value: BottomNavigationBarType.shifting,
-                child: new Text('Shifting')
+                child: new Text('Shifting'),
               )
             ]
           )
         ]
       ),
       body: _buildBody(),
-      bottomNavigationBar: botNavBar
+      bottomNavigationBar: botNavBar,
     );
   }
 }

examples/flutter_gallery/lib/demo/progress_indicator_demo.dart

@@ -11,7 +11,7 @@ class ProgressIndicatorDemo extends StatefulWidget {
   _ProgressIndicatorDemoState createState() => new _ProgressIndicatorDemoState();
 }
 
-class _ProgressIndicatorDemoState extends State<ProgressIndicatorDemo> {
+class _ProgressIndicatorDemoState extends State<ProgressIndicatorDemo> with SingleTickerProviderStateMixin {
   AnimationController _controller;
   Animation<double> _animation;
 
@@ -19,7 +19,8 @@ class _ProgressIndicatorDemoState extends State<ProgressIndicatorDemo> {
   void initState() {
     super.initState();
     _controller = new AnimationController(
-      duration: const Duration(milliseconds: 1500)
+      duration: const Duration(milliseconds: 1500),
+      vsync: this,
     )..forward();
 
     _animation = new CurvedAnimation(

examples/flutter_gallery/lib/gallery/home.dart

@@ -95,19 +95,20 @@ class GalleryHome extends StatefulWidget {
   GalleryHomeState createState() => new GalleryHomeState();
 }
 
-class GalleryHomeState extends State<GalleryHome> {
+class GalleryHomeState extends State<GalleryHome> with SingleTickerProviderStateMixin {
-  static final Key _homeKey = new ValueKey<String>("Gallery Home");
+  static final Key _homeKey = new ValueKey<String>('Gallery Home');
   static final GlobalKey<ScrollableState> _scrollableKey = new GlobalKey<ScrollableState>();
 
-  final AnimationController _controller = new AnimationController(
+  AnimationController _controller;
-    duration: const Duration(milliseconds: 600),
-    debugLabel: "preview banner"
-  );
 
   @override
   void initState() {
     super.initState();
-    _controller.forward();
+    _controller = new AnimationController(
+      duration: const Duration(milliseconds: 600),
+      debugLabel: 'preview banner',
+      vsync: this,
+    )..forward();
   }
 
   @override

examples/layers/rendering/spinning_square.dart

@@ -9,6 +9,13 @@ import 'dart:math' as math;
 
 import 'package:flutter/animation.dart';
 import 'package:flutter/rendering.dart';
+import 'package:flutter/scheduler.dart';
+
+class NonStopVSync implements TickerProvider {
+  const NonStopVSync();
+  @override
+  Ticker createTicker(TickerCallback onTick) => new Ticker(onTick);
+}
 
 void main() {
   // We first create a render object that represents a green box.
@@ -41,7 +48,8 @@ void main() {
   // To make the square spin, we use an animation that repeats every 1800
   // milliseconds.
   AnimationController animation = new AnimationController(
-    duration: const Duration(milliseconds: 1800)
+    duration: const Duration(milliseconds: 1800),
+    vsync: const NonStopVSync(),
   )..repeat();
   // The animation will produce a value between 0.0 and 1.0 each frame, but we
   // want to rotate the square using a value between 0.0 and math.PI. To change

examples/layers/services/isolate.dart

@@ -206,7 +206,7 @@ class IsolateExampleWidget extends StatefulWidget {
 }
 
 // Main application state.
-class IsolateExampleState extends State<StatefulWidget> {
+class IsolateExampleState extends State<StatefulWidget> with SingleTickerProviderStateMixin {
 
   String _status = 'Idle';
   String _label = 'Start';
@@ -219,7 +219,8 @@ class IsolateExampleState extends State<StatefulWidget> {
   void initState() {
     super.initState();
     _animation = new AnimationController(
-      duration: const Duration(milliseconds: 3600)
+      duration: const Duration(milliseconds: 3600),
+      vsync: this,
     )..repeat();
     _calculationManager = new CalculationManager(
       onProgressListener: _handleProgressUpdate,

examples/layers/widgets/spinning_square.dart

@@ -9,7 +9,7 @@ class SpinningSquare extends StatefulWidget {
   _SpinningSquareState createState() => new _SpinningSquareState();
 }
 
-class _SpinningSquareState extends State<SpinningSquare> {
+class _SpinningSquareState extends State<SpinningSquare> with SingleTickerProviderStateMixin {
   AnimationController _animation;
 
   @override
@@ -19,7 +19,8 @@ class _SpinningSquareState extends State<SpinningSquare> {
     // represents an entire turn of the square whereas in the other examples
     // we used 0.0 -> math.PI, which is only half a turn.
     _animation = new AnimationController(
-      duration: const Duration(milliseconds: 3600)
+      duration: const Duration(milliseconds: 3600),
+      vsync: this,
     )..repeat();
   }
 

packages/flutter/lib/src/animation/animation_controller.dart

@@ -5,8 +5,9 @@
 import 'dart:async';
 import 'dart:ui' as ui show lerpDouble;
 
-import 'package:flutter/scheduler.dart';
 import 'package:flutter/physics.dart';
+import 'package:flutter/scheduler.dart';
+import 'package:meta/meta.dart';
 
 import 'animation.dart';
 import 'curves.dart';
@@ -19,7 +20,7 @@ enum _AnimationDirection {
   forward,
 
   /// The animation is running backwards, from end to beginning.
-  reverse
+  reverse,
 }
 
 /// A controller for an animation.
@@ -40,29 +41,33 @@ class AnimationController extends Animation<double>
 
   /// Creates an animation controller.
   ///
-  /// * value is the initial value of the animation.
+  /// * [value] is the initial value of the animation.
-  /// * duration is the length of time this animation should last.
+  /// * [duration] is the length of time this animation should last.
-  /// * debugLabel is a string to help identify this animation during debugging (used by toString).
+  /// * [debugLabel] is a string to help identify this animation during debugging (used by [toString]).
-  /// * lowerBound is the smallest value this animation can obtain and the value at which this animation is deemed to be dismissed.
+  /// * [lowerBound] is the smallest value this animation can obtain and the value at which this animation is deemed to be dismissed.
-  /// * upperBound is the largest value this animation can obtain and the value at which this animation is deemed to be completed.
+  /// * [upperBound] is the largest value this animation can obtain and the value at which this animation is deemed to be completed.
+  /// * `vsync` is the [TickerProvider] for the current context. It can be changed by calling [resync].
   AnimationController({
     double value,
     this.duration,
     this.debugLabel,
     this.lowerBound: 0.0,
-    this.upperBound: 1.0
+    this.upperBound: 1.0,
+    @required TickerProvider vsync,
   }) {
     assert(upperBound >= lowerBound);
+    assert(vsync != null);
     _direction = _AnimationDirection.forward;
-    _ticker = new Ticker(_tick);
+    _ticker = vsync.createTicker(_tick);
     _internalSetValue(value ?? lowerBound);
   }
 
   /// Creates an animation controller with no upper or lower bound for its value.
   ///
-  /// * value is the initial value of the animation.
+  /// * [value] is the initial value of the animation.
-  /// * duration is the length of time this animation should last.
+  /// * [duration] is the length of time this animation should last.
-  /// * debugLabel is a string to help identify this animation during debugging (used by toString).
+  /// * [debugLabel] is a string to help identify this animation during debugging (used by [toString]).
+  /// * `vsync` is the [TickerProvider] for the current context. It can be changed by calling [resync].
   ///
   /// This constructor is most useful for animations that will be driven using a
   /// physics simulation, especially when the physics simulation has no
@@ -70,12 +75,14 @@ class AnimationController extends Animation<double>
   AnimationController.unbounded({
     double value: 0.0,
     this.duration,
-    this.debugLabel
+    this.debugLabel,
+    @required TickerProvider vsync,
   }) : lowerBound = double.NEGATIVE_INFINITY,
        upperBound = double.INFINITY {
     assert(value != null);
+    assert(vsync != null);
     _direction = _AnimationDirection.forward;
-    _ticker = new Ticker(_tick);
+    _ticker = vsync.createTicker(_tick);
     _internalSetValue(value);
   }
 
@@ -98,6 +105,14 @@ class AnimationController extends Animation<double>
   Duration duration;
 
   Ticker _ticker;
+
+  /// Recreates the [Ticker] with the new [TickerProvider].
+  void resync(TickerProvider vsync) {
+    Ticker oldTicker = _ticker;
+    _ticker = vsync.createTicker(_tick);
+    _ticker.absorbTicker(oldTicker);
+  }
+
   Simulation _simulation;
 
   /// The current value of the animation.
@@ -145,7 +160,12 @@ class AnimationController extends Animation<double>
   Duration _lastElapsedDuration;
 
   /// Whether this animation is currently animating in either the forward or reverse direction.
-  bool get isAnimating => _ticker.isTicking;
+  ///
+  /// This is separate from whether it is actively ticking. An animation
+  /// controller's ticker might get muted, in which case the animation
+  /// controller's callbacks will no longer fire even though time is continuing
+  /// to pass. See [Ticker.muted] and [TickerMode].
+  bool get isAnimating => _ticker.isActive;
 
   _AnimationDirection _direction;
 
@@ -239,16 +259,21 @@ class AnimationController extends Animation<double>
   }
 
   /// Stops running this animation.
+  ///
+  /// This does not trigger any notifications. The animation stops in its
+  /// current state.
   void stop() {
     _simulation = null;
     _lastElapsedDuration = null;
     _ticker.stop();
   }
 
-  /// Stops running this animation.
+  /// Release the resources used by this object. The object is no longer usable
+  /// after this method is called.
   @override
   void dispose() {
-    stop();
+    _ticker.dispose();
+    super.dispose();
   }
 
   AnimationStatus _lastReportedStatus = AnimationStatus.dismissed;
@@ -277,9 +302,10 @@ class AnimationController extends Animation<double>
   @override
   String toStringDetails() {
     String paused = isAnimating ? '' : '; paused';
+    String silenced = _ticker.muted ? '; silenced' : '';
     String label = debugLabel == null ? '' : '; for $debugLabel';
     String more = '${super.toStringDetails()} ${value.toStringAsFixed(3)}';
-    return '$more$paused$label';
+    return '$more$paused$silenced$label';
   }
 }
 

packages/flutter/lib/src/animation/animations.dart

@@ -524,6 +524,7 @@ class TrainHoppingAnimation extends Animation<double>
     _currentTrain = null;
     _nextTrain?.removeListener(_valueChangeHandler);
     _nextTrain = null;
+    super.dispose();
   }
 
   @override

packages/flutter/lib/src/animation/listener_helpers.dart

@@ -4,6 +4,8 @@
 
 import 'dart:ui' show VoidCallback;
 
+import 'package:meta/meta.dart';
+
 import 'animation.dart';
 
 abstract class _ListenerMixin {
@@ -50,8 +52,10 @@ abstract class AnimationEagerListenerMixin implements _ListenerMixin {
   @override
   void didUnregisterListener() { }
 
-  /// Release any resources used by this object.
+  /// Release the resources used by this object. The object is no longer usable
-  void dispose();
+  /// after this method is called.
+  @mustCallSuper
+  void dispose() { }
 }
 
 /// A mixin that implements the addListener/removeListener protocol and notifies

packages/flutter/lib/src/material/bottom_navigation_bar.dart

@@ -139,7 +139,7 @@ class BottomNavigationBar extends StatefulWidget {
   BottomNavigationBarState createState() => new BottomNavigationBarState();
 }
 
-class BottomNavigationBarState extends State<BottomNavigationBar> {
+class BottomNavigationBarState extends State<BottomNavigationBar> with TickerProviderStateMixin {
   List<AnimationController> _controllers;
   List<CurvedAnimation> animations;
   double _weight;
@@ -156,7 +156,8 @@ class BottomNavigationBarState extends State<BottomNavigationBar> {
     super.initState();
     _controllers = new List<AnimationController>.generate(config.labels.length, (int index) {
       return new AnimationController(
-        duration: kThemeAnimationDuration
+        duration: kThemeAnimationDuration,
+        vsync: this,
       )..addListener(_rebuild);
     });
     animations = new List<CurvedAnimation>.generate(config.labels.length, (int index) {
@@ -166,9 +167,7 @@ class BottomNavigationBarState extends State<BottomNavigationBar> {
         reverseCurve: Curves.fastOutSlowIn.flipped
       );
     });
-
     _controllers[config.currentIndex].value = 1.0;
-
     _backgroundColor = config.labels[config.currentIndex].backgroundColor;
   }
 
@@ -271,7 +270,8 @@ class BottomNavigationBarState extends State<BottomNavigationBar> {
         new _Circle(
           state: this,
           index: index,
-          color: config.labels[index].backgroundColor
+          color: config.labels[index].backgroundColor,
+          vsync: this,
         )..controller.addStatusListener((AnimationStatus status) {
           if (status == AnimationStatus.completed) {
             setState(() {
@@ -289,7 +289,6 @@ class BottomNavigationBarState extends State<BottomNavigationBar> {
     if (config.currentIndex != oldConfig.currentIndex) {
       if (config.type == BottomNavigationBarType.shifting)
         _pushCircle(config.currentIndex);
-
       _controllers[oldConfig.currentIndex].reverse();
       _controllers[config.currentIndex].forward();
     }
@@ -298,7 +297,6 @@ class BottomNavigationBarState extends State<BottomNavigationBar> {
   @override
   Widget build(BuildContext context) {
     Widget bottomNavigation;
-
     switch (config.type) {
       case BottomNavigationBarType.fixed:
         final List<Widget> children = <Widget>[];
@@ -311,7 +309,6 @@ class BottomNavigationBarState extends State<BottomNavigationBar> {
                 themeData.primaryColor : themeData.accentColor
           )
         );
-
         for (int i = 0; i < config.labels.length; i += 1) {
           children.add(
             new Flexible(
@@ -329,16 +326,16 @@ class BottomNavigationBarState extends State<BottomNavigationBar> {
                         margin: new EdgeInsets.only(
                           top: new Tween<double>(
                             begin: 8.0,
-                            end: 6.0
+                            end: 6.0,
-                          ).evaluate(animations[i])
+                          ).evaluate(animations[i]),
                         ),
                         child: new IconTheme(
                           data: new IconThemeData(
-                            color: colorTween.evaluate(animations[i])
+                            color: colorTween.evaluate(animations[i]),
                           ),
-                          child: config.labels[i].icon
+                          child: config.labels[i].icon,
-                        )
+                        ),
-                      )
+                      ),
                     ),
                     new Align(
                       alignment: FractionalOffset.bottomCenter,
@@ -347,41 +344,36 @@ class BottomNavigationBarState extends State<BottomNavigationBar> {
                         child: new DefaultTextStyle(
                           style: new TextStyle(
                             fontSize: 14.0,
-                            color: colorTween.evaluate(animations[i])
+                            color: colorTween.evaluate(animations[i]),
                           ),
                           child: new Transform(
                             transform: new Matrix4.diagonal3(new Vector3.all(
                               new Tween<double>(
                                 begin: 0.85,
                                 end: 1.0,
-                              ).evaluate(animations[i])
+                              ).evaluate(animations[i]),
                             )),
                             alignment: FractionalOffset.bottomCenter,
-                            child: config.labels[i].title
+                            child: config.labels[i].title,
-                          )
+                          ),
-                        )
+                        ),
-                      )
+                      ),
-                    )
+                    ),
-                  ]
+                  ],
-                )
+                ),
-              )
+              ),
-            )
+            ),
           );
         }
-
         bottomNavigation = new SizedBox(
           width: _maxWidth,
-          child: new Row(
+          child: new Row(children: children),
-            children: children
-          )
         );
-
         break;
+
       case BottomNavigationBarType.shifting:
         final List<Widget> children = <Widget>[];
-
         _computeWeight();
-
         for (int i = 0; i < config.labels.length; i += 1) {
           children.add(
             new Flexible(
@@ -402,16 +394,16 @@ class BottomNavigationBarState extends State<BottomNavigationBar> {
                         margin: new EdgeInsets.only(
                           top: new Tween<double>(
                             begin: 18.0,
-                            end: 6.0
+                            end: 6.0,
-                          ).evaluate(animations[i])
+                          ).evaluate(animations[i]),
                         ),
                         child: new IconTheme(
                           data: new IconThemeData(
                             color: Colors.white
                           ),
-                          child: config.labels[i].icon
+                          child: config.labels[i].icon,
-                        )
+                        ),
-                      )
+                      ),
                     ),
                     new Align(
                       alignment: FractionalOffset.bottomCenter,
@@ -425,24 +417,22 @@ class BottomNavigationBarState extends State<BottomNavigationBar> {
                               color: Colors.white
                             ),
                             child: config.labels[i].title
-                          )
+                          ),
-                        )
+                        ),
-                      )
+                      ),
-                    )
+                    ),
-                  ]
+                  ],
-                )
+                ),
-              )
+              ),
-            )
+            ),
           );
         }
-
         bottomNavigation = new SizedBox(
           width: _maxWidth,
           child: new Row(
             children: children
           )
         );
-
         break;
     }
 
@@ -467,20 +457,20 @@ class BottomNavigationBarState extends State<BottomNavigationBar> {
                   child: new CustomPaint(
                     painter: new _RadialPainter(
                       circles: _circles.toList()
-                    )
+                    ),
-                  )
+                  ),
                 ),
                 new Material( // Splashes.
                   type: MaterialType.transparency,
                   child: new Center(
                     child: bottomNavigation
-                  )
+                  ),
-                )
+                ),
-              ]
+              ],
-            )
+            ),
-          )
+          ),
-        )
+        ),
-      ]
+      ],
     );
   }
 }
@@ -489,20 +479,21 @@ class _Circle {
   _Circle({
     this.state,
     this.index,
-    this.color
+    this.color,
+    @required TickerProvider vsync,
   }) {
     assert(this.state != null);
     assert(this.index != null);
     assert(this.color != null);
 
     controller = new AnimationController(
-      duration: kThemeAnimationDuration
+      duration: kThemeAnimationDuration,
+      vsync: vsync,
     );
     animation = new CurvedAnimation(
       parent: controller,
       curve: Curves.fastOutSlowIn
     );
-
     controller.forward();
   }
 

packages/flutter/lib/src/material/bottom_sheet.dart

@@ -78,10 +78,11 @@ class BottomSheet extends StatefulWidget {
   _BottomSheetState createState() => new _BottomSheetState();
 
   /// Creates an animation controller suitable for controlling a [BottomSheet].
-  static AnimationController createAnimationController() {
+  static AnimationController createAnimationController(TickerProvider vsync) {
     return new AnimationController(
       duration: _kBottomSheetDuration,
-      debugLabel: 'BottomSheet'
+      debugLabel: 'BottomSheet',
+      vsync: vsync,
     );
   }
 }
@@ -222,7 +223,7 @@ class _ModalBottomSheetRoute<T> extends PopupRoute<T> {
   @override
   AnimationController createAnimationController() {
     assert(_animationController == null);
-    _animationController = BottomSheet.createAnimationController();
+    _animationController = BottomSheet.createAnimationController(navigator.overlay);
     return _animationController;
   }
 

packages/flutter/lib/src/material/checkbox.dart

@@ -30,7 +30,7 @@ import 'toggleable.dart';
 ///  * [Slider]
 ///  * <https://www.google.com/design/spec/components/selection-controls.html#selection-controls-checkbox>
 ///  * <https://www.google.com/design/spec/components/lists-controls.html#lists-controls-types-of-list-controls>
-class Checkbox extends StatelessWidget {
+class Checkbox extends StatefulWidget {
   /// Creates a material design checkbox.
   ///
   /// The checkbox itself does not maintain any state. Instead, when the state of
@@ -68,15 +68,21 @@ class Checkbox extends StatelessWidget {
   /// The width of a checkbox widget.
   static const double width = 18.0;
 
+  @override
+  _CheckboxState createState() => new _CheckboxState();
+}
+
+class _CheckboxState extends State<Checkbox> with TickerProviderStateMixin {
   @override
   Widget build(BuildContext context) {
     assert(debugCheckHasMaterial(context));
     ThemeData themeData = Theme.of(context);
     return new _CheckboxRenderObjectWidget(
-      value: value,
+      value: config.value,
-      activeColor: activeColor ?? themeData.accentColor,
+      activeColor: config.activeColor ?? themeData.accentColor,
-      inactiveColor: onChanged != null ? themeData.unselectedWidgetColor : themeData.disabledColor,
+      inactiveColor: config.onChanged != null ? themeData.unselectedWidgetColor : themeData.disabledColor,
-      onChanged: onChanged
+      onChanged: config.onChanged,
+      vsync: this,
     );
   }
 }
@@ -84,27 +90,31 @@ class Checkbox extends StatelessWidget {
 class _CheckboxRenderObjectWidget extends LeafRenderObjectWidget {
   _CheckboxRenderObjectWidget({
     Key key,
-    this.value,
+    @required this.value,
-    this.activeColor,
+    @required this.activeColor,
-    this.inactiveColor,
+    @required this.inactiveColor,
-    this.onChanged
+    @required this.onChanged,
+    @required this.vsync,
   }) : super(key: key) {
     assert(value != null);
     assert(activeColor != null);
     assert(inactiveColor != null);
+    assert(vsync != null);
   }
 
   final bool value;
   final Color activeColor;
   final Color inactiveColor;
   final ValueChanged<bool> onChanged;
+  final TickerProvider vsync;
 
   @override
   _RenderCheckbox createRenderObject(BuildContext context) => new _RenderCheckbox(
     value: value,
     activeColor: activeColor,
     inactiveColor: inactiveColor,
-    onChanged: onChanged
+    onChanged: onChanged,
+    vsync: vsync,
   );
 
   @override
@@ -113,7 +123,8 @@ class _CheckboxRenderObjectWidget extends LeafRenderObjectWidget {
       ..value = value
       ..activeColor = activeColor
       ..inactiveColor = inactiveColor
-      ..onChanged = onChanged;
+      ..onChanged = onChanged
+      ..vsync = vsync;
   }
 }
 
@@ -127,13 +138,15 @@ class _RenderCheckbox extends RenderToggleable {
     bool value,
     Color activeColor,
     Color inactiveColor,
-    ValueChanged<bool> onChanged
+    ValueChanged<bool> onChanged,
+    @required TickerProvider vsync,
   }): super(
     value: value,
     activeColor: activeColor,
     inactiveColor: inactiveColor,
     onChanged: onChanged,
-    size: const Size(2 * kRadialReactionRadius, 2 * kRadialReactionRadius)
+    size: const Size(2 * kRadialReactionRadius, 2 * kRadialReactionRadius),
+    vsync: vsync,
   );
 
   @override

packages/flutter/lib/src/material/data_table.dart

@@ -675,7 +675,7 @@ class _SortArrow extends StatefulWidget {
   _SortArrowState createState() => new _SortArrowState();
 }
 
-class _SortArrowState extends State<_SortArrow> {
+class _SortArrowState extends State<_SortArrow> with TickerProviderStateMixin {
 
   AnimationController _opacityController;
   Animation<double> _opacityAnimation;
@@ -691,7 +691,8 @@ class _SortArrowState extends State<_SortArrow> {
     super.initState();
     _opacityAnimation = new CurvedAnimation(
       parent: _opacityController = new AnimationController(
-        duration: config.duration
+        duration: config.duration,
+        vsync: this,
       ),
       curve: Curves.fastOutSlowIn
     )
@@ -702,7 +703,8 @@ class _SortArrowState extends State<_SortArrow> {
       end: math.PI
     ).animate(new CurvedAnimation(
       parent: _orientationController = new AnimationController(
-        duration: config.duration
+        duration: config.duration,
+        vsync: this,
       ),
       curve: Curves.easeIn
     ))

packages/flutter/lib/src/material/drawer.dart

@@ -111,11 +111,11 @@ class DrawerController extends StatefulWidget {
 /// State for a [DrawerController].
 ///
 /// Typically used by a [Scaffold] to [open] and [close] the drawer.
-class DrawerControllerState extends State<DrawerController> {
+class DrawerControllerState extends State<DrawerController> with SingleTickerProviderStateMixin {
   @override
   void initState() {
     super.initState();
-    _controller = new AnimationController(duration: _kBaseSettleDuration)
+    _controller = new AnimationController(duration: _kBaseSettleDuration, vsync: this)
       ..addListener(_animationChanged)
       ..addStatusListener(_animationStatusChanged);
   }

packages/flutter/lib/src/material/expand_icon.dart

@@ -60,14 +60,14 @@ class ExpandIcon extends StatefulWidget {
   _ExpandIconState createState() => new _ExpandIconState();
 }
 
-class _ExpandIconState extends State<ExpandIcon> {
+class _ExpandIconState extends State<ExpandIcon> with SingleTickerProviderStateMixin {
   AnimationController _controller;
   Animation<double> _iconTurns;
 
   @override
   void initState() {
     super.initState();
-    _controller = new AnimationController(duration: kThemeAnimationDuration);
+    _controller = new AnimationController(duration: kThemeAnimationDuration, vsync: this);
     _iconTurns = new Tween<double>(begin: 0.0, end: 0.5).animate(
       new CurvedAnimation(
         parent: _controller,

packages/flutter/lib/src/material/material.dart

@@ -6,6 +6,7 @@ import 'dart:math' as math;
 
 import 'package:flutter/rendering.dart';
 import 'package:flutter/widgets.dart';
+import 'package:meta/meta.dart';
 import 'package:vector_math/vector_math_64.dart';
 
 import 'constants.dart';
@@ -219,7 +220,7 @@ class Material extends StatefulWidget {
   }
 }
 
-class _MaterialState extends State<Material> {
+class _MaterialState extends State<Material> with TickerProviderStateMixin {
   final GlobalKey _inkFeatureRenderer = new GlobalKey(debugLabel: 'ink renderer');
 
   Color _getBackgroundColor(BuildContext context) {
@@ -254,7 +255,8 @@ class _MaterialState extends State<Material> {
       child: new _InkFeatures(
         key: _inkFeatureRenderer,
         color: backgroundColor,
-        child: contents
+        child: contents,
+        vsync: this,
       )
     );
     if (config.type == MaterialType.circle) {
@@ -295,7 +297,14 @@ const double _kSplashConfirmedVelocity = 1.0; // logical pixels per millisecond
 const double _kSplashInitialSize = 0.0; // logical pixels
 
 class _RenderInkFeatures extends RenderProxyBox implements MaterialInkController {
-  _RenderInkFeatures({ RenderBox child, this.color }) : super(child);
+  _RenderInkFeatures({ RenderBox child, @required this.vsync, this.color }) : super(child) {
+    assert(vsync != null);
+  }
+
+  // This class should exist in a 1:1 relationship with a MaterialState object,
+  // since there's no current support for dynamically changing the ticker
+  // provider.
+  final TickerProvider vsync;
 
   // This is here to satisfy the MaterialInkController contract.
   // The actual painting of this color is done by a Container in the
@@ -338,7 +347,8 @@ class _RenderInkFeatures extends RenderProxyBox implements MaterialInkController
       targetRadius: radius,
       clipCallback: clipCallback,
       repositionToReferenceBox: !containedInkWell,
-      onRemoved: onRemoved
+      onRemoved: onRemoved,
+      vsync: vsync,
     );
     addInkFeature(splash);
     return splash;
@@ -366,7 +376,8 @@ class _RenderInkFeatures extends RenderProxyBox implements MaterialInkController
       color: color,
       shape: shape,
       rectCallback: rectCallback,
-      onRemoved: onRemoved
+      onRemoved: onRemoved,
+      vsync: vsync,
     );
     addInkFeature(highlight);
     return highlight;
@@ -405,16 +416,27 @@ class _RenderInkFeatures extends RenderProxyBox implements MaterialInkController
 }
 
 class _InkFeatures extends SingleChildRenderObjectWidget {
-  _InkFeatures({ Key key, this.color, Widget child }) : super(key: key, child: child);
+  _InkFeatures({ Key key, this.color, Widget child, @required this.vsync }) : super(key: key, child: child);
+
+  // This widget must be owned by a MaterialState, which must be provided as the vsync.
+  // This relationship must be 1:1 and cannot change for the lifetime of the MaterialState.
 
   final Color color;
 
+  final TickerProvider vsync;
+
   @override
-  _RenderInkFeatures createRenderObject(BuildContext context) => new _RenderInkFeatures(color: color);
+  _RenderInkFeatures createRenderObject(BuildContext context) {
+    return new _RenderInkFeatures(
+      color: color,
+      vsync: vsync
+    );
+  }
 
   @override
   void updateRenderObject(BuildContext context, _RenderInkFeatures renderObject) {
     renderObject.color = color;
+    assert(vsync == renderObject.vsync);
   }
 }
 
@@ -488,17 +510,17 @@ class _InkSplash extends InkFeature implements InkSplash {
     this.targetRadius,
     this.clipCallback,
     this.repositionToReferenceBox,
-    VoidCallback onRemoved
+    VoidCallback onRemoved,
+    @required TickerProvider vsync,
   }) : super(controller: controller, referenceBox: referenceBox, onRemoved: onRemoved) {
-    _radiusController = new AnimationController(duration: _kUnconfirmedSplashDuration)
+    _radiusController = new AnimationController(duration: _kUnconfirmedSplashDuration, vsync: vsync)
       ..addListener(controller.markNeedsPaint)
       ..forward();
     _radius = new Tween<double>(
       begin: _kSplashInitialSize,
       end: targetRadius
     ).animate(_radiusController);
-
+    _alphaController = new AnimationController(duration: _kHighlightFadeDuration, vsync: vsync)
-    _alphaController = new AnimationController(duration: _kHighlightFadeDuration)
       ..addListener(controller.markNeedsPaint)
       ..addStatusListener(_handleAlphaStatusChanged);
     _alpha = new IntTween(
@@ -578,10 +600,11 @@ class _InkHighlight extends InkFeature implements InkHighlight {
     this.rectCallback,
     Color color,
     this.shape,
-    VoidCallback onRemoved
+    VoidCallback onRemoved,
+    @required TickerProvider vsync,
   }) : _color = color,
        super(controller: controller, referenceBox: referenceBox, onRemoved: onRemoved) {
-    _alphaController = new AnimationController(duration: _kHighlightFadeDuration)
+    _alphaController = new AnimationController(duration: _kHighlightFadeDuration, vsync: vsync)
       ..addListener(controller.markNeedsPaint)
       ..addStatusListener(_handleAlphaStatusChanged)
       ..forward();

packages/flutter/lib/src/material/mergeable_material.dart

@@ -136,7 +136,7 @@ class _AnimationTuple {
   double gapStart;
 }
 
-class _MergeableMaterialState extends State<MergeableMaterial> {
+class _MergeableMaterialState extends State<MergeableMaterial> with TickerProviderStateMixin {
   List<MergeableMaterialItem> _children;
   final Map<LocalKey, _AnimationTuple> _animationTuples =
       <LocalKey, _AnimationTuple>{};
@@ -157,7 +157,8 @@ class _MergeableMaterialState extends State<MergeableMaterial> {
 
   void _initGap(MaterialGap gap) {
     final AnimationController controller = new AnimationController(
-      duration: kThemeAnimationDuration
+      duration: kThemeAnimationDuration,
+      vsync: this,
     );
 
     final CurvedAnimation startAnimation = new CurvedAnimation(

packages/flutter/lib/src/material/overscroll_indicator.dart

@@ -121,13 +121,9 @@ class OverscrollIndicator extends StatefulWidget {
   _OverscrollIndicatorState createState() => new _OverscrollIndicatorState();
 }
 
-class _OverscrollIndicatorState extends State<OverscrollIndicator> {
+class _OverscrollIndicatorState extends State<OverscrollIndicator> with SingleTickerProviderStateMixin {
-  final AnimationController _extentAnimation = new AnimationController(
-    lowerBound: _kMinIndicatorExtent,
-    upperBound: _kMaxIndicatorExtent,
-    duration: _kNormalHideDuration
-  );
 
+  AnimationController _extentAnimation;
   bool _scrollUnderway = false;
   Timer _hideTimer;
   Axis _scrollDirection;
@@ -136,6 +132,17 @@ class _OverscrollIndicatorState extends State<OverscrollIndicator> {
   double _maxScrollOffset;
   Point _dragPosition;
 
+  @override
+  void initState() {
+    super.initState();
+    _extentAnimation = new AnimationController(
+      lowerBound: _kMinIndicatorExtent,
+      upperBound: _kMaxIndicatorExtent,
+      duration: _kNormalHideDuration,
+      vsync: this,
+    );
+  }
+
   void _hide([Duration duration=_kTimeoutHideDuration]) {
     _scrollUnderway = false;
     _hideTimer?.cancel();

packages/flutter/lib/src/material/popup_menu.dart

@@ -216,7 +216,7 @@ class CheckedPopupMenuItem<T> extends PopupMenuItem<T> {
   _CheckedPopupMenuItemState<T> createState() => new _CheckedPopupMenuItemState<T>();
 }
 
-class _CheckedPopupMenuItemState<T> extends _PopupMenuItemState<CheckedPopupMenuItem<T>> {
+class _CheckedPopupMenuItemState<T> extends _PopupMenuItemState<CheckedPopupMenuItem<T>> with SingleTickerProviderStateMixin {
   static const Duration _kFadeDuration = const Duration(milliseconds: 150);
   AnimationController _controller;
   Animation<double> get _opacity => _controller.view;
@@ -224,7 +224,7 @@ class _CheckedPopupMenuItemState<T> extends _PopupMenuItemState<CheckedPopupMenu
   @override
   void initState() {
     super.initState();
-    _controller = new AnimationController(duration: _kFadeDuration)
+    _controller = new AnimationController(duration: _kFadeDuration, vsync: this)
       ..value = config.checked ? 1.0 : 0.0
       ..addListener(() => setState(() { /* animation changed */ }));
   }

packages/flutter/lib/src/material/progress_indicator.dart

@@ -146,7 +146,7 @@ class LinearProgressIndicator extends ProgressIndicator {
   _LinearProgressIndicatorState createState() => new _LinearProgressIndicatorState();
 }
 
-class _LinearProgressIndicatorState extends State<LinearProgressIndicator> {
+class _LinearProgressIndicatorState extends State<LinearProgressIndicator> with SingleTickerProviderStateMixin {
   Animation<double> _animation;
   AnimationController _controller;
 
@@ -154,7 +154,8 @@ class _LinearProgressIndicatorState extends State<LinearProgressIndicator> {
   void initState() {
     super.initState();
     _controller = new AnimationController(
-      duration: const Duration(milliseconds: 1500)
+      duration: const Duration(milliseconds: 1500),
+      vsync: this,
     )..repeat();
     _animation = new CurvedAnimation(parent: _controller, curve: Curves.fastOutSlowIn);
   }
@@ -310,13 +311,16 @@ final Animatable<int> _kStepTween = new StepTween(begin: 0, end: 5);
 
 final Animatable<double> _kRotationTween = new CurveTween(curve: new SawTooth(5));
 
-class _CircularProgressIndicatorState extends State<CircularProgressIndicator> {
+class _CircularProgressIndicatorState extends State<CircularProgressIndicator> with SingleTickerProviderStateMixin {
   AnimationController _controller;
 
   @override
   void initState() {
     super.initState();
-    _controller = _buildController();
+    _controller = new AnimationController(
+      duration: const Duration(milliseconds: 6666),
+      vsync: this,
+    )..repeat();
   }
 
   @override
@@ -325,10 +329,6 @@ class _CircularProgressIndicatorState extends State<CircularProgressIndicator> {
     super.dispose();
   }
 
-  AnimationController _buildController() {
-    return new AnimationController(duration: const Duration(milliseconds: 6666))..repeat();
-  }
-
   Widget _buildIndicator(BuildContext context, double headValue, double tailValue, int stepValue, double rotationValue) {
     return new Container(
       constraints: new BoxConstraints(

packages/flutter/lib/src/material/radio.dart

@@ -35,7 +35,7 @@ const double _kInnerRadius = 5.0;
 ///  * [Slider]
 ///  * [Switch]
 ///  * <https://www.google.com/design/spec/components/selection-controls.html#selection-controls-radio-button>
-class Radio<T> extends StatelessWidget {
+class Radio<T> extends StatefulWidget {
   /// Creates a material design radio button.
   ///
   /// The radio button itself does not maintain any state. Instead, when the state
@@ -77,7 +77,12 @@ class Radio<T> extends StatelessWidget {
   /// Defaults to accent color of the current [Theme].
   final Color activeColor;
 
-  bool get _enabled => onChanged != null;
+  @override
+  _RadioState<T> createState() => new _RadioState<T>();
+}
+
+class _RadioState<T> extends State<Radio<T>> with TickerProviderStateMixin {
+  bool get _enabled => config.onChanged != null;
 
   Color _getInactiveColor(ThemeData themeData) {
     return _enabled ? themeData.unselectedWidgetColor : themeData.disabledColor;
@@ -85,7 +90,7 @@ class Radio<T> extends StatelessWidget {
 
   void _handleChanged(bool selected) {
     if (selected)
-      onChanged(value);
+      config.onChanged(config.value);
   }
 
   @override
@@ -93,12 +98,13 @@ class Radio<T> extends StatelessWidget {
     assert(debugCheckHasMaterial(context));
     ThemeData themeData = Theme.of(context);
     return new Semantics(
-      checked: value == groupValue,
+      checked: config.value == config.groupValue,
       child: new _RadioRenderObjectWidget(
-        selected: value == groupValue,
+        selected: config.value == config.groupValue,
-        activeColor: activeColor ?? themeData.accentColor,
+        activeColor: config.activeColor ?? themeData.accentColor,
         inactiveColor: _getInactiveColor(themeData),
-        onChanged: _enabled ? _handleChanged : null
+        onChanged: _enabled ? _handleChanged : null,
+        vsync: this,
       )
     );
   }
@@ -107,27 +113,31 @@ class Radio<T> extends StatelessWidget {
 class _RadioRenderObjectWidget extends LeafRenderObjectWidget {
   _RadioRenderObjectWidget({
     Key key,
-    this.selected,
+    @required this.selected,
-    this.activeColor,
+    @required this.activeColor,
-    this.inactiveColor,
+    @required this.inactiveColor,
-    this.onChanged
+    this.onChanged,
+    @required this.vsync,
   }) : super(key: key) {
     assert(selected != null);
     assert(activeColor != null);
     assert(inactiveColor != null);
+    assert(vsync != null);
   }
 
   final bool selected;
   final Color inactiveColor;
   final Color activeColor;
   final ValueChanged<bool> onChanged;
+  final TickerProvider vsync;
 
   @override
   _RenderRadio createRenderObject(BuildContext context) => new _RenderRadio(
     value: selected,
     activeColor: activeColor,
     inactiveColor: inactiveColor,
-    onChanged: onChanged
+    onChanged: onChanged,
+    vsync: vsync,
   );
 
   @override
@@ -136,7 +146,8 @@ class _RadioRenderObjectWidget extends LeafRenderObjectWidget {
       ..value = selected
       ..activeColor = activeColor
       ..inactiveColor = inactiveColor
-      ..onChanged = onChanged;
+      ..onChanged = onChanged
+      ..vsync = vsync;
   }
 }
 
@@ -145,13 +156,15 @@ class _RenderRadio extends RenderToggleable {
     bool value,
     Color activeColor,
     Color inactiveColor,
-    ValueChanged<bool> onChanged
+    ValueChanged<bool> onChanged,
+    @required TickerProvider vsync,
   }): super(
     value: value,
     activeColor: activeColor,
     inactiveColor: inactiveColor,
     onChanged: onChanged,
-    size: const Size(2 * kRadialReactionRadius, 2 * kRadialReactionRadius)
+    size: const Size(2 * kRadialReactionRadius, 2 * kRadialReactionRadius),
+    vsync: vsync,
   );
 
   @override

packages/flutter/lib/src/material/refresh_indicator.dart

@@ -138,9 +138,9 @@ class RefreshIndicator extends StatefulWidget {
 
 /// Contains the state for a [RefreshIndicator]. This class can be used to
 /// programmatically show the refresh indicator, see the [show] method.
-class RefreshIndicatorState extends State<RefreshIndicator> {
+class RefreshIndicatorState extends State<RefreshIndicator> with TickerProviderStateMixin {
-  final AnimationController _sizeController = new AnimationController();
+  AnimationController _sizeController;
-  final AnimationController _scaleController = new AnimationController();
+  AnimationController _scaleController;
   Animation<double> _sizeFactor;
   Animation<double> _scaleFactor;
   Animation<double> _value;
@@ -154,15 +154,16 @@ class RefreshIndicatorState extends State<RefreshIndicator> {
   @override
   void initState() {
     super.initState();
-    _sizeFactor = new Tween<double>(begin: 0.0, end: _kDragSizeFactorLimit).animate(_sizeController);
-    _scaleFactor = new Tween<double>(begin: 1.0, end: 0.0).animate(_scaleController);
 
-    // The "value" of the circular progress indicator during a drag.
+    _sizeController = new AnimationController(vsync: this);
-    _value = new Tween<double>(
+    _sizeFactor = new Tween<double>(begin: 0.0, end: _kDragSizeFactorLimit).animate(_sizeController);
+    _value = new Tween<double>( // The "value" of the circular progress indicator during a drag.
       begin: 0.0,
       end: 0.75
-    )
+    ).animate(_sizeController);
-    .animate(_sizeController);
+
+    _scaleController = new AnimationController(vsync: this);
+    _scaleFactor = new Tween<double>(begin: 1.0, end: 0.0).animate(_scaleController);
   }
 
   @override

packages/flutter/lib/src/material/scaffold.dart

@@ -169,10 +169,9 @@ class _FloatingActionButtonTransition extends StatefulWidget {
   _FloatingActionButtonTransitionState createState() => new _FloatingActionButtonTransitionState();
 }
 
-class _FloatingActionButtonTransitionState extends State<_FloatingActionButtonTransition> {
+class _FloatingActionButtonTransitionState extends State<_FloatingActionButtonTransition> with TickerProviderStateMixin {
-  final AnimationController _previousController = new AnimationController(duration: _kFloatingActionButtonSegue);
+  AnimationController _previousController;
-  final AnimationController _currentController = new AnimationController(duration: _kFloatingActionButtonSegue);
+  AnimationController _currentController;
-
   CurvedAnimation _previousAnimation;
   CurvedAnimation _currentAnimation;
   Widget _previousChild;
@@ -180,21 +179,29 @@ class _FloatingActionButtonTransitionState extends State<_FloatingActionButtonTr
   @override
   void initState() {
     super.initState();
-    // If we start out with a child, have the child appear fully visible instead
-    // of animating in.
-    if (config.child != null)
-      _currentController.value = 1.0;
 
+    _previousController = new AnimationController(
+      duration: _kFloatingActionButtonSegue,
+      vsync: this,
+    )..addStatusListener(_handleAnimationStatusChanged);
     _previousAnimation = new CurvedAnimation(
       parent: _previousController,
       curve: Curves.easeIn
     );
+
+    _currentController = new AnimationController(
+      duration: _kFloatingActionButtonSegue,
+      vsync: this,
+    );
     _currentAnimation = new CurvedAnimation(
       parent: _currentController,
       curve: Curves.easeIn
     );
 
-    _previousController.addStatusListener(_handleAnimationStatusChanged);
+    // If we start out with a child, have the child appear fully visible instead
+    // of animating in.
+    if (config.child != null)
+      _currentController.value = 1.0;
   }
 
   @override
@@ -357,7 +364,7 @@ class Scaffold extends StatefulWidget {
 ///
 /// Can display [SnackBar]s and [BottomSheet]s. Retrieve a [ScaffoldState] from
 /// the current [BuildContext] using [Scaffold.of].
-class ScaffoldState extends State<Scaffold> {
+class ScaffoldState extends State<Scaffold> with TickerProviderStateMixin {
 
   static final Object _kScaffoldStorageIdentifier = new Object();
 
@@ -401,7 +408,7 @@ class ScaffoldState extends State<Scaffold> {
   /// will be added to a queue and displayed after the earlier snack bars have
   /// closed.
   ScaffoldFeatureController<SnackBar, Null> showSnackBar(SnackBar snackbar) {
-    _snackBarController ??= SnackBar.createAnimationController()
+    _snackBarController ??= SnackBar.createAnimationController(vsync: this)
       ..addStatusListener(_handleSnackBarStatusChange);
     if (_snackBars.isEmpty) {
       assert(_snackBarController.isDismissed);
@@ -475,7 +482,7 @@ class ScaffoldState extends State<Scaffold> {
 
   // PERSISTENT BOTTOM SHEET API
 
-  final List<Widget> _dismissedBottomSheets = <Widget>[];
+  final List<_PersistentBottomSheet> _dismissedBottomSheets = <_PersistentBottomSheet>[];
   PersistentBottomSheetController<dynamic> _currentBottomSheet;
 
   /// Shows a persistent material design bottom sheet.
@@ -504,7 +511,7 @@ class ScaffoldState extends State<Scaffold> {
     }
     Completer<dynamic/*=T*/> completer = new Completer<dynamic/*=T*/>();
     GlobalKey<_PersistentBottomSheetState> bottomSheetKey = new GlobalKey<_PersistentBottomSheetState>();
-    AnimationController controller = BottomSheet.createAnimationController()
+    AnimationController controller = BottomSheet.createAnimationController(this)
       ..forward();
     _PersistentBottomSheet bottomSheet;
     LocalHistoryEntry entry = new LocalHistoryEntry(
@@ -554,7 +561,7 @@ class ScaffoldState extends State<Scaffold> {
   @override
   void initState() {
     super.initState();
-    _appBarController = new AnimationController();
+    _appBarController = new AnimationController(vsync: this);
     // Use an explicit identifier to guard against the possibility that the
     // Scaffold's key is recreated by the Widget that creates the Scaffold.
     List<double> scrollValues = PageStorage.of(context)?.readState(context,
@@ -569,11 +576,15 @@ class ScaffoldState extends State<Scaffold> {
 
   @override
   void dispose() {
-    _appBarController.stop();
+    _appBarController.dispose();
-    _snackBarController?.stop();
+    _snackBarController?.dispose();
     _snackBarController = null;
     _snackBarTimer?.cancel();
     _snackBarTimer = null;
+    for (_PersistentBottomSheet bottomSheet in _dismissedBottomSheets)
+      bottomSheet.animationController.dispose();
+    if (_currentBottomSheet != null)
+      _currentBottomSheet._widget.animationController.dispose();
     PageStorage.of(context)?.writeState(context, <double>[_scrollOffset, _scrollOffsetDelta],
       identifier: _kScaffoldStorageIdentifier
     );

packages/flutter/lib/src/material/scrollbar.dart

@@ -95,8 +95,8 @@ class Scrollbar extends StatefulWidget {
   _ScrollbarState createState() => new _ScrollbarState();
 }
 
-class _ScrollbarState extends State<Scrollbar> {
+class _ScrollbarState extends State<Scrollbar> with SingleTickerProviderStateMixin {
-  final AnimationController _fade = new AnimationController(duration: _kScrollbarThumbFadeDuration);
+  AnimationController _fade;
   CurvedAnimation _opacity;
   double _scrollOffset;
   Axis _scrollDirection;
@@ -106,6 +106,7 @@ class _ScrollbarState extends State<Scrollbar> {
   @override
   void initState() {
     super.initState();
+    _fade = new AnimationController(duration: _kScrollbarThumbFadeDuration, vsync: this);
     _opacity = new CurvedAnimation(parent: _fade, curve: Curves.fastOutSlowIn);
   }
 

packages/flutter/lib/src/material/slider.dart

@@ -39,7 +39,7 @@ import 'typography.dart';
 ///  * [Radio]
 ///  * [Switch]
 ///  * <https://www.google.com/design/spec/components/sliders.html>
-class Slider extends StatelessWidget {
+class Slider extends StatefulWidget {
   /// Creates a material design slider.
   ///
   /// The slider itself does not maintain any state. Instead, when the state of
@@ -107,20 +107,26 @@ class Slider extends StatelessWidget {
   /// Defaults to accent color of the current [Theme].
   final Color activeColor;
 
+  @override
+  _SliderState createState() => new _SliderState();
+}
+
+class _SliderState extends State<Slider> with TickerProviderStateMixin {
   void _handleChanged(double value) {
-    assert(onChanged != null);
+    assert(config.onChanged != null);
-    onChanged(value * (max - min) + min);
+    config.onChanged(value * (config.max - config.min) + config.min);
   }
 
   @override
   Widget build(BuildContext context) {
     assert(debugCheckHasMaterial(context));
     return new _SliderRenderObjectWidget(
-      value: (value - min) / (max - min),
+      value: (config.value - config.min) / (config.max - config.min),
-      divisions: divisions,
+      divisions: config.divisions,
-      label: label,
+      label: config.label,
-      activeColor: activeColor ?? Theme.of(context).accentColor,
+      activeColor: config.activeColor ?? Theme.of(context).accentColor,
-      onChanged: onChanged != null ? _handleChanged : null
+      onChanged: config.onChanged != null ? _handleChanged : null,
+      vsync: this,
     );
   }
 }
@@ -132,7 +138,8 @@ class _SliderRenderObjectWidget extends LeafRenderObjectWidget {
     this.divisions,
     this.label,
     this.activeColor,
-    this.onChanged
+    this.onChanged,
+    this.vsync,
   }) : super(key: key);
 
   final double value;
@@ -140,6 +147,7 @@ class _SliderRenderObjectWidget extends LeafRenderObjectWidget {
   final String label;
   final Color activeColor;
   final ValueChanged<double> onChanged;
+  final TickerProvider vsync;
 
   @override
   _RenderSlider createRenderObject(BuildContext context) => new _RenderSlider(
@@ -147,7 +155,8 @@ class _SliderRenderObjectWidget extends LeafRenderObjectWidget {
     divisions: divisions,
     label: label,
     activeColor: activeColor,
-    onChanged: onChanged
+    onChanged: onChanged,
+    vsync: vsync,
   );
 
   @override
@@ -158,6 +167,8 @@ class _SliderRenderObjectWidget extends LeafRenderObjectWidget {
       ..label = label
       ..activeColor = activeColor
       ..onChanged = onChanged;
+    // Ticker provider cannot change since there's a 1:1 relationship between
+    // the _SliderRenderObjectWidget object and the _SliderState object.
   }
 }
 
@@ -199,7 +210,8 @@ class _RenderSlider extends RenderConstrainedBox implements SemanticActionHandle
     int divisions,
     String label,
     Color activeColor,
-    this.onChanged
+    this.onChanged,
+    TickerProvider vsync,
   }) : _value = value,
        _divisions = divisions,
        _activeColor = activeColor,
@@ -210,14 +222,18 @@ class _RenderSlider extends RenderConstrainedBox implements SemanticActionHandle
       ..onStart = _handleDragStart
       ..onUpdate = _handleDragUpdate
       ..onEnd = _handleDragEnd;
-    _reactionController = new AnimationController(duration: kRadialReactionDuration);
+    _reactionController = new AnimationController(
+      duration: kRadialReactionDuration,
+      vsync: vsync,
+    );
     _reaction = new CurvedAnimation(
       parent: _reactionController,
       curve: Curves.fastOutSlowIn
     )..addListener(markNeedsPaint);
     _position = new AnimationController(
       value: value,
-      duration: _kDiscreteTransitionDuration
+      duration: _kDiscreteTransitionDuration,
+      vsync: vsync,
     )..addListener(markNeedsPaint);
   }
 

packages/flutter/lib/src/material/snack_bar.dart

@@ -204,10 +204,11 @@ class SnackBar extends StatelessWidget {
   // API for Scaffold.addSnackBar():
 
   /// Creates an animation controller useful for driving a snack bar's entrance and exit animation.
-  static AnimationController createAnimationController() {
+  static AnimationController createAnimationController({ @required TickerProvider vsync }) {
     return new AnimationController(
       duration: _kSnackBarTransitionDuration,
-      debugLabel: 'SnackBar'
+      debugLabel: 'SnackBar',
+      vsync: vsync,
     );
   }
 

packages/flutter/lib/src/material/stepper.dart

@@ -176,7 +176,7 @@ class Stepper extends StatefulWidget {
   _StepperState createState() => new _StepperState();
 }
 
-class _StepperState extends State<Stepper> {
+class _StepperState extends State<Stepper> with TickerProviderStateMixin {
   List<GlobalKey> _keys;
   final Map<int, StepState> _oldStates = new Map<int, StepState>();
 
@@ -608,7 +608,8 @@ class _StepperState extends State<Stepper> {
                   new AnimatedSize(
                     curve: Curves.fastOutSlowIn,
                     duration: kThemeAnimationDuration,
-                    child: config.steps[config.currentStep].content
+                    vsync: this,
+                    child: config.steps[config.currentStep].content,
                   ),
                   _buildVerticalControls()
                 ]

packages/flutter/lib/src/material/switch.dart

@@ -32,7 +32,7 @@ import 'toggleable.dart';
 ///  * [Radio]
 ///  * [Slider]
 ///  * <https://www.google.com/design/spec/components/selection-controls.html#selection-controls-switch>
-class Switch extends StatelessWidget {
+class Switch extends StatefulWidget {
   /// Creates a material design switch.
   ///
   /// The switch itself does not maintain any state. Instead, when the state of
@@ -74,18 +74,31 @@ class Switch extends StatelessWidget {
   /// An image to use on the thumb of this switch when the switch is off.
   final ImageProvider inactiveThumbImage;
 
+  @override
+  _SwitchState createState() => new _SwitchState();
+
+  @override
+  void debugFillDescription(List<String> description) {
+    super.debugFillDescription(description);
+    description.add('value: ${value ? "on" : "off"}');
+    if (onChanged == null)
+      description.add('disabled');
+  }
+}
+
+class _SwitchState extends State<Switch> with TickerProviderStateMixin {
   @override
   Widget build(BuildContext context) {
     assert(debugCheckHasMaterial(context));
     final ThemeData themeData = Theme.of(context);
     final bool isDark = themeData.brightness == Brightness.dark;
 
-    final Color activeThumbColor = activeColor ?? themeData.accentColor;
+    final Color activeThumbColor = config.activeColor ?? themeData.accentColor;
     final Color activeTrackColor = activeThumbColor.withAlpha(0x80);
 
     Color inactiveThumbColor;
     Color inactiveTrackColor;
-    if (onChanged != null) {
+    if (config.onChanged != null) {
       inactiveThumbColor = isDark ? Colors.grey[400] : Colors.grey[50];
       inactiveTrackColor = isDark ? Colors.white30 : Colors.black26;
     } else {
@@ -94,25 +107,18 @@ class Switch extends StatelessWidget {
     }
 
     return new _SwitchRenderObjectWidget(
-      value: value,
+      value: config.value,
       activeColor: activeThumbColor,
       inactiveColor: inactiveThumbColor,
-      activeThumbImage: activeThumbImage,
+      activeThumbImage: config.activeThumbImage,
-      inactiveThumbImage: inactiveThumbImage,
+      inactiveThumbImage: config.inactiveThumbImage,
       activeTrackColor: activeTrackColor,
       inactiveTrackColor: inactiveTrackColor,
       configuration: createLocalImageConfiguration(context),
-      onChanged: onChanged
+      onChanged: config.onChanged,
+      vsync: this,
     );
   }
-
-  @override
-  void debugFillDescription(List<String> description) {
-    super.debugFillDescription(description);
-    description.add('value: ${value ? "on" : "off"}');
-    if (onChanged == null)
-      description.add('disabled');
-  }
 }
 
 class _SwitchRenderObjectWidget extends LeafRenderObjectWidget {
@@ -126,7 +132,8 @@ class _SwitchRenderObjectWidget extends LeafRenderObjectWidget {
     this.activeTrackColor,
     this.inactiveTrackColor,
     this.configuration,
-    this.onChanged
+    this.onChanged,
+    this.vsync,
   }) : super(key: key);
 
   final bool value;
@@ -138,6 +145,7 @@ class _SwitchRenderObjectWidget extends LeafRenderObjectWidget {
   final Color inactiveTrackColor;
   final ImageConfiguration configuration;
   final ValueChanged<bool> onChanged;
+  final TickerProvider vsync;
 
   @override
   _RenderSwitch createRenderObject(BuildContext context) => new _RenderSwitch(
@@ -149,7 +157,8 @@ class _SwitchRenderObjectWidget extends LeafRenderObjectWidget {
     activeTrackColor: activeTrackColor,
     inactiveTrackColor: inactiveTrackColor,
     configuration: configuration,
-    onChanged: onChanged
+    onChanged: onChanged,
+    vsync: vsync,
   );
 
   @override
@@ -163,7 +172,8 @@ class _SwitchRenderObjectWidget extends LeafRenderObjectWidget {
       ..activeTrackColor = activeTrackColor
       ..inactiveTrackColor = inactiveTrackColor
       ..configuration = configuration
-      ..onChanged = onChanged;
+      ..onChanged = onChanged
+      ..vsync = vsync;
   }
 }
 
@@ -184,7 +194,8 @@ class _RenderSwitch extends RenderToggleable {
     Color activeTrackColor,
     Color inactiveTrackColor,
     ImageConfiguration configuration,
-    ValueChanged<bool> onChanged
+    ValueChanged<bool> onChanged,
+    @required TickerProvider vsync,
   }) : _activeThumbImage = activeThumbImage,
        _inactiveThumbImage = inactiveThumbImage,
        _activeTrackColor = activeTrackColor,
@@ -195,7 +206,8 @@ class _RenderSwitch extends RenderToggleable {
          activeColor: activeColor,
          inactiveColor: inactiveColor,
          onChanged: onChanged,
-         size: const Size(_kSwitchWidth, _kSwitchHeight)
+         size: const Size(_kSwitchWidth, _kSwitchHeight),
+         vsync: vsync,
        ) {
     _drag = new HorizontalDragGestureRecognizer()
       ..onStart = _handleDragStart

packages/flutter/lib/src/material/tabs.dart

@@ -523,26 +523,27 @@ class TabBarSelection<T> extends StatefulWidget {
 ///
 /// Subclasses of [TabBarSelection] typically use [State] objects that extend
 /// this class.
-class TabBarSelectionState<T> extends State<TabBarSelection<T>> {
+class TabBarSelectionState<T> extends State<TabBarSelection<T>> with SingleTickerProviderStateMixin {
+
+  // Both the TabBar and TabBarView classes access _controller because they
+  // alternately drive selection progress between tabs.
+  AnimationController _controller;
 
   /// An animation that updates as the selected tab changes.
   Animation<double> get animation => _controller.view;
 
-  // Both the TabBar and TabBarView classes access _controller because they
-  // alternately drive selection progress between tabs.
-  final AnimationController _controller = new AnimationController(duration: _kTabBarScroll, value: 1.0);
   final Map<T, int> _valueToIndex = new Map<T, int>();
 
-  void _initValueToIndex() {
-    _valueToIndex.clear();
-    int index = 0;
-    for(T value in values)
-      _valueToIndex[value] = index++;
-  }
-
   @override
   void initState() {
     super.initState();
+
+    _controller = new AnimationController(
+      duration: _kTabBarScroll,
+      value: 1.0,
+      vsync: this,
+    );
+
     _value = config.value ?? PageStorage.of(context)?.readState(context) ?? values.first;
 
     // If the selection's values have changed since the selected value was saved with
@@ -561,6 +562,13 @@ class TabBarSelectionState<T> extends State<TabBarSelection<T>> {
       _initValueToIndex();
   }
 
+  void _initValueToIndex() {
+    _valueToIndex.clear();
+    int index = 0;
+    for (T value in values)
+      _valueToIndex[value] = index++;
+  }
+
   void _writeValue() {
     PageStorage.of(context)?.writeState(context, _value);
   }

packages/flutter/lib/src/material/time_picker.dart

@@ -410,11 +410,14 @@ class _Dial extends StatefulWidget {
   _DialState createState() => new _DialState();
 }
 
-class _DialState extends State<_Dial> {
+class _DialState extends State<_Dial> with SingleTickerProviderStateMixin {
   @override
   void initState() {
     super.initState();
-    _thetaController = new AnimationController(duration: _kDialAnimateDuration);
+    _thetaController = new AnimationController(
+      duration: _kDialAnimateDuration,
+      vsync: this,
+    );
     _thetaTween = new Tween<double>(begin: _getThetaForTime(config.selectedTime));
     _theta = _thetaTween.animate(new CurvedAnimation(
       parent: _thetaController,

packages/flutter/lib/src/material/toggleable.dart

@@ -5,6 +5,8 @@
 import 'package:flutter/animation.dart';
 import 'package:flutter/gestures.dart';
 import 'package:flutter/rendering.dart';
+import 'package:flutter/scheduler.dart';
+import 'package:meta/meta.dart';
 
 import 'constants.dart';
 
@@ -26,38 +28,88 @@ abstract class RenderToggleable extends RenderConstrainedBox implements Semantic
     Size size,
     Color activeColor,
     Color inactiveColor,
-    ValueChanged<bool> onChanged
+    ValueChanged<bool> onChanged,
+    @required TickerProvider vsync,
   }) : _value = value,
        _activeColor = activeColor,
        _inactiveColor = inactiveColor,
        _onChanged = onChanged,
+       _vsync = vsync,
        super(additionalConstraints: new BoxConstraints.tight(size)) {
     assert(value != null);
     assert(activeColor != null);
     assert(inactiveColor != null);
+    assert(vsync != null);
     _tap = new TapGestureRecognizer()
       ..onTapDown = _handleTapDown
       ..onTap = _handleTap
       ..onTapUp = _handleTapUp
       ..onTapCancel = _handleTapCancel;
-
     _positionController = new AnimationController(
       duration: _kToggleDuration,
-      value: _value ? 1.0 : 0.0
+      value: value ? 1.0 : 0.0,
+      vsync: vsync,
     );
     _position = new CurvedAnimation(
       parent: _positionController,
-      curve: Curves.linear
+      curve: Curves.linear,
     )..addListener(markNeedsPaint)
      ..addStatusListener(_handlePositionStateChanged);
-
+    _reactionController = new AnimationController(
-    _reactionController = new AnimationController(duration: kRadialReactionDuration);
+      duration: kRadialReactionDuration,
+      vsync: vsync,
+    );
     _reaction = new CurvedAnimation(
       parent: _reactionController,
-      curve: Curves.fastOutSlowIn
+      curve: Curves.fastOutSlowIn,
     )..addListener(markNeedsPaint);
   }
 
+  /// Used by subclasses to manipulate the visual value of the control.
+  ///
+  /// Some controls respond to user input by updating their visual value. For
+  /// example, the thumb of a switch moves from one position to another when
+  /// dragged. These controls manipulate this animation controller to update
+  /// their [position] and eventually trigger an [onChanged] callback when the
+  /// animation reaches either 0.0 or 1.0.
+  @protected
+  AnimationController get positionController => _positionController;
+  AnimationController _positionController;
+
+  /// The visual value of the control.
+  ///
+  /// When the control is inactive, the [value] is false and this animation has
+  /// the value 0.0. When the control is active, the value is [true] and this
+  /// animation has the value 1.0. When the control is changing from inactive
+  /// to active (or vice versa), [value] is the target value and this animation
+  /// gradually updates from 0.0 to 1.0 (or vice versa).
+  CurvedAnimation get position => _position;
+  CurvedAnimation _position;
+
+  /// Used by subclasses to control the radial reaction animation.
+  ///
+  /// Some controls have a radial ink reaction to user input. This animation
+  /// controller can be used to start or stop these ink reactions.
+  ///
+  /// Subclasses should call [paintRadialReaction] to actually paint the radial
+  /// reaction.
+  @protected
+  AnimationController get reactionController => _reactionController;
+  AnimationController _reactionController;
+  Animation<double> _reaction;
+
+  /// The [TickerProvider] for the [AnimationController]s that run the animations.
+  TickerProvider get vsync => _vsync;
+  TickerProvider _vsync;
+  set vsync(TickerProvider value) {
+    assert(value != null);
+    if (value == _vsync)
+      return;
+    _vsync = value;
+    positionController.resync(vsync);
+    reactionController.resync(vsync);
+  }
+
   /// Whether this control is current "active" (checked, on, selected) or "inactive" (unchecked, off, not selected).
   ///
   /// When the value changes, this object starts the [positionController] and
@@ -138,50 +190,17 @@ abstract class RenderToggleable extends RenderConstrainedBox implements Semantic
   /// grey color and its value cannot be changed.
   bool get isInteractive => onChanged != null;
 
-  /// The visual value of the control.
-  ///
-  /// When the control is inactive, the [value] is false and this animation has
-  /// the value 0.0. When the control is active, the value is [true] and this
-  /// animation has the value 1.0. When the control is changing from inactive
-  /// to active (or vice versa), [value] is the target value and this animation
-  /// gradually updates from 0.0 to 1.0 (or vice versa).
-  CurvedAnimation get position => _position;
-  CurvedAnimation _position;
-
-  /// Used by subclasses to manipulate the visual value of the control.
-  ///
-  /// Some controls respond to user input by updating their visual value. For
-  /// example, the thumb of a switch moves from one position to another when
-  /// dragged. These controls manipulate this animation controller to update
-  /// their [position] and eventually trigger an [onChanged] callback when the
-  /// animation reaches either 0.0 or 1.0.
-  AnimationController get positionController => _positionController;
-  AnimationController _positionController;
-
-  /// Used by subclasses to control the radial reaction animation.
-  ///
-  /// Some controls have a radial ink reaction to user input. This animation
-  /// controller can be used to start or stop these ink reactions.
-  ///
-  /// Subclasses should call [paintRadialReaction] to actually paint the radial
-  /// reaction.
-  AnimationController get reactionController => _reactionController;
-  AnimationController _reactionController;
-  Animation<double> _reaction;
-
   TapGestureRecognizer _tap;
   Point _downPosition;
 
   @override
   void attach(PipelineOwner owner) {
     super.attach(owner);
-    if (_positionController != null) {
+    if (value)
-      if (value)
+      _positionController.forward();
-        _positionController.forward();
+    else
-      else
+      _positionController.reverse();
-        _positionController.reverse();
+    if (isInteractive) {
-    }
-    if (_reactionController != null && isInteractive) {
       switch (_reactionController.status) {
         case AnimationStatus.forward:
           _reactionController.forward();
@@ -199,8 +218,8 @@ abstract class RenderToggleable extends RenderConstrainedBox implements Semantic
 
   @override
   void detach() {
-    _positionController?.stop();
+    _positionController.stop();
-    _reactionController?.stop();
+    _reactionController.stop();
     super.detach();
   }
 

packages/flutter/lib/src/material/tooltip.dart

@@ -93,7 +93,7 @@ class Tooltip extends StatefulWidget {
   }
 }
 
-class _TooltipState extends State<Tooltip> {
+class _TooltipState extends State<Tooltip> with SingleTickerProviderStateMixin {
   AnimationController _controller;
   OverlayEntry _entry;
   Timer _timer;
@@ -101,7 +101,7 @@ class _TooltipState extends State<Tooltip> {
   @override
   void initState() {
     super.initState();
-    _controller = new AnimationController(duration: _kFadeDuration)
+    _controller = new AnimationController(duration: _kFadeDuration, vsync: this)
       ..addStatusListener(_handleStatusChanged);
   }
 
@@ -178,7 +178,7 @@ class _TooltipState extends State<Tooltip> {
   void dispose() {
     if (_entry != null)
       _removeEntry();
-    _controller.stop();
+    _controller.dispose();
     super.dispose();
   }
 

packages/flutter/lib/src/material/two_level_list.dart

@@ -142,7 +142,7 @@ class TwoLevelSublist extends StatefulWidget {
   _TwoLevelSublistState createState() => new _TwoLevelSublistState();
 }
 
-class _TwoLevelSublistState extends State<TwoLevelSublist> {
+class _TwoLevelSublistState extends State<TwoLevelSublist> with SingleTickerProviderStateMixin {
   AnimationController _controller;
   CurvedAnimation _easeOutAnimation;
   CurvedAnimation _easeInAnimation;
@@ -157,7 +157,7 @@ class _TwoLevelSublistState extends State<TwoLevelSublist> {
   @override
   void initState() {
     super.initState();
-    _controller = new AnimationController(duration: _kExpand);
+    _controller = new AnimationController(duration: _kExpand, vsync: this);
     _easeOutAnimation = new CurvedAnimation(parent: _controller, curve: Curves.easeOut);
     _easeInAnimation = new CurvedAnimation(parent: _controller, curve: Curves.easeIn);
     _borderColor = new ColorTween(begin: Colors.transparent);
@@ -173,7 +173,7 @@ class _TwoLevelSublistState extends State<TwoLevelSublist> {
 
   @override
   void dispose() {
-    _controller.stop();
+    _controller.dispose();
     super.dispose();
   }
 
@@ -243,8 +243,8 @@ class _TwoLevelSublistState extends State<TwoLevelSublist> {
       ..end = config.backgroundColor ?? Colors.transparent;
 
     return new AnimatedBuilder(
-        animation: _controller.view,
+      animation: _controller.view,
-        builder: buildList
+      builder: buildList
     );
   }
 }

packages/flutter/lib/src/rendering/animated_size.dart

@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 import 'package:flutter/animation.dart';
+import 'package:flutter/scheduler.dart';
 import 'package:meta/meta.dart';
 
 import 'box.dart';
@@ -10,29 +11,41 @@ import 'object.dart';
 import 'shifted_box.dart';
 
 /// A render object that animates its size to its child's size over a given
-/// [duration] and with a given [curve]. In case the child's size is animating
+/// [duration] and with a given [curve]. If the child's size itself animates
-/// as opposed to abruptly changing size, the parent behaves like a normal
+/// (i.e. if it changes size two frames in a row, as opposed to abruptly
-/// container.
+/// changing size in one frame then remaining that size in subsequent frames),
+/// this render object sizes itself to fit the child instead of animating
+/// itself.
 ///
-/// In case the child overflows the current animated size of the parent, it gets
+/// When the child overflows the current animated size of this render object, it
-/// clipped automatically.
+/// is clipped.
 class RenderAnimatedSize extends RenderAligningShiftedBox {
   /// Creates a render object that animates its size to match its child.
-  /// The [duration] and [curve] arguments define the animation. The [alignment]
+  /// The [duration] and [curve] arguments define the animation.
-  /// argument is used to align the child in the case where the parent is not
+  ///
+  /// The [alignment] argument is used to align the child when the parent is not
   /// (yet) the same size as the child.
   ///
-  /// The arguments [duration], [curve], and [alignment] should not be null.
+  /// The [duration] is required.
+  ///
+  /// The [vsync] should specify a [TickerProvider] for the animation
+  /// controller.
+  ///
+  /// The arguments [duration], [curve], [alignment], and [vsync] must
+  /// not be null.
   RenderAnimatedSize({
+    @required TickerProvider vsync,
+    @required Duration duration,
     Curve curve: Curves.linear,
-    RenderBox child,
     FractionalOffset alignment: FractionalOffset.center,
-    @required Duration duration
+    RenderBox child,
-  }) : super(child: child, alignment: alignment) {
+  }) : _vsync = vsync, super(child: child, alignment: alignment) {
+    assert(vsync != null);
     assert(duration != null);
     assert(curve != null);
     _controller = new AnimationController(
-      duration: duration
+      vsync: vsync,
+      duration: duration,
     )..addListener(() {
       if (_controller.value != _lastValue)
         markNeedsLayout();
@@ -68,6 +81,17 @@ class RenderAnimatedSize extends RenderAligningShiftedBox {
     _animation.curve = value;
   }
 
+  /// The [TickerProvider] for the [AnimationController] that runs the animation.
+  TickerProvider get vsync => _vsync;
+  TickerProvider _vsync;
+  set vsync(TickerProvider value) {
+    assert(value != null);
+    if (value == _vsync)
+      return;
+    _vsync = value;
+    _controller.resync(vsync);
+  }
+
   @override
   void attach(PipelineOwner owner) {
     super.attach(owner);
@@ -104,8 +128,7 @@ class RenderAnimatedSize extends RenderAligningShiftedBox {
         size = child.size;
         _controller.stop();
       } else {
-        // Don't register first change (i.e. when _targetSize == _sourceSize)
+        // Don't register first change as a last-frame change.
-        // as a last-frame change.
         if (_sizeTween.end != _sizeTween.begin)
           _didChangeTargetSizeLastFrame = true;
 

packages/flutter/lib/src/rendering/binding.dart

@@ -198,7 +198,7 @@ abstract class RendererBinding extends BindingBase implements SchedulerBinding,
   /// then invokes post-frame callbacks (registered with [addPostFrameCallback].
   ///
   /// Some bindings (for example, the [WidgetsBinding]) add extra steps to this
-  /// list.
+  /// list (for example, see [WidgetsBinding.beginFrame]).
   //
   // When editing the above, also update widgets/binding.dart's copy.
   @protected

packages/flutter/lib/src/scheduler/binding.dart

@@ -86,6 +86,45 @@ class _FrameCallbackEntry {
   StackTrace debugStack;
 }
 
+/// The various phases that a [SchedulerBinding] goes through during
+/// [SchedulerBinding.handleBeginFrame].
+///
+/// This is exposed by [SchedulerBinding.schedulerPhase].
+///
+/// The values of this enum are ordered in the same order as the phases occur,
+/// so their relative index values can be compared to each other.
+///
+/// See also [WidgetsBinding.beginFrame].
+enum SchedulerPhase {
+  /// No frame is being processed. Tasks (scheduled by
+  /// [WidgetsBinding.scheduleTask]), microtasks (scheduled by
+  /// [scheduleMicrotask]), [Timer] callbacks, event handlers (e.g. from user
+  /// input), and other callbacks (e.g. from [Future]s, [Stream]s, and the like)
+  /// may be executing.
+  idle,
+
+  /// The transient callbacks (scheduled by
+  /// [WidgetsBinding.scheduleFrameCallback] and
+  /// [WidgetsBinding.addFrameCallback]) are currently executing.
+  ///
+  /// Typically, these callbacks handle updating objects to new animation states.
+  transientCallbacks,
+
+  /// The persistent callbacks (scheduled by
+  /// [WidgetsBinding.addPersistentFrameCallback]) are currently executing.
+  ///
+  /// Typically, this is the build/layout/paint pipeline. See
+  /// [WidgetsBinding.beginFrame].
+  persistentCallbacks,
+
+  /// The post-frame callbacks (scheduled by
+  /// [WidgetsBinding.addPostFrameCallback]) are currently executing.
+  ///
+  /// Typically, these callbacks handle cleanup and scheduling of work for the
+  /// next frame.
+  postFrameCallbacks,
+}
+
 /// Scheduler for running the following:
 ///
 /// * _Frame callbacks_, triggered by the system's
@@ -402,9 +441,9 @@ abstract class SchedulerBinding extends BindingBase {
   bool get hasScheduledFrame => _hasScheduledFrame;
   bool _hasScheduledFrame = false;
 
-  /// Whether this scheduler is currently producing a frame in [handleBeginFrame].
+  /// The phase that the scheduler is currently operating under.
-  bool get isProducingFrame => _isProducingFrame;
+  SchedulerPhase get schedulerPhase => _schedulerPhase;
-  bool _isProducingFrame = false;
+  SchedulerPhase _schedulerPhase = SchedulerPhase.idle;
 
   /// Schedules a new frame using [scheduleFrame] if this object is not
   /// currently producing a frame.
@@ -412,7 +451,7 @@ abstract class SchedulerBinding extends BindingBase {
   /// After this is called, the framework ensures that the end of the
   /// [handleBeginFrame] function will (eventually) be reached.
   void ensureVisualUpdate() {
-    if (_isProducingFrame)
+    if (schedulerPhase != SchedulerPhase.idle)
       return;
     scheduleFrame();
   }
@@ -530,20 +569,21 @@ abstract class SchedulerBinding extends BindingBase {
       return true;
     });
 
-    assert(!_isProducingFrame);
+    assert(schedulerPhase == SchedulerPhase.idle);
-    _isProducingFrame = true;
     _hasScheduledFrame = false;
     try {
 
       // TRANSIENT FRAME CALLBACKS
+      _schedulerPhase = SchedulerPhase.transientCallbacks;
       _invokeTransientFrameCallbacks(_currentFrameTimeStamp);
 
       // PERSISTENT FRAME CALLBACKS
+      _schedulerPhase = SchedulerPhase.persistentCallbacks;
       for (FrameCallback callback in _persistentCallbacks)
         _invokeFrameCallback(callback, _currentFrameTimeStamp);
-      _isProducingFrame = false;
 
       // POST-FRAME CALLBACKS
+      _schedulerPhase = SchedulerPhase.postFrameCallbacks;
       List<FrameCallback> localPostFrameCallbacks =
           new List<FrameCallback>.from(_postFrameCallbacks);
       _postFrameCallbacks.clear();
@@ -551,7 +591,7 @@ abstract class SchedulerBinding extends BindingBase {
         _invokeFrameCallback(callback, _currentFrameTimeStamp);
 
     } finally {
-      _isProducingFrame = false; // just in case we throw before setting it above
+      _schedulerPhase = SchedulerPhase.idle;
       _currentFrameTimeStamp = null;
       Timeline.finishSync();
       assert(() {
@@ -567,7 +607,7 @@ abstract class SchedulerBinding extends BindingBase {
 
   void _invokeTransientFrameCallbacks(Duration timeStamp) {
     Timeline.startSync('Animate');
-    assert(_isProducingFrame);
+    assert(schedulerPhase == SchedulerPhase.transientCallbacks);
     Map<int, _FrameCallbackEntry> callbacks = _transientCallbacks;
     _transientCallbacks = new Map<int, _FrameCallbackEntry>();
     callbacks.forEach((int id, _FrameCallbackEntry callbackEntry) {

packages/flutter/lib/src/scheduler/ticker.dart

@@ -4,6 +4,9 @@
 
 import 'dart:async';
 
+import 'package:flutter/foundation.dart';
+import 'package:meta/meta.dart';
+
 import 'binding.dart';
 
 /// Signature for the [onTick] constructor argument of the [Ticker] class.
@@ -12,35 +15,112 @@ import 'binding.dart';
 /// at the time of the callback being called.
 typedef void TickerCallback(Duration elapsed);
 
+/// An interface implemented by classes that can vend [Ticker] objects.
+abstract class TickerProvider {
+  /// Abstract const constructor. This constructor enables subclasses to provide
+  /// const constructors so that they can be used in const expressions.
+  const TickerProvider();
+
+  /// Creates a ticker with the given callback.
+  ///
+  /// The kind of ticker provided depends on the kind of ticker provider.
+  Ticker createTicker(TickerCallback onTick);
+}
+
 /// Calls its callback once per animation frame.
 ///
 /// When created, a ticker is initially disabled. Call [start] to
 /// enable the ticker.
 ///
-/// See also [SchedulerBinding.scheduleFrameCallback].
+/// A [Ticker] can be silenced by setting [muted] to true. While silenced, time
+/// still elapses, and [start] and [stop] can still be called, but no callbacks
+/// are called.
+///
+/// Tickers are driven by the [SchedulerBinding]. See
+/// [SchedulerBinding.scheduleFrameCallback].
 class Ticker {
   /// Creates a ticker that will call [onTick] once per frame while running.
-  Ticker(TickerCallback onTick) : _onTick = onTick;
+  ///
-
+  /// An optional label can be provided for debugging purposes. That label
-  final TickerCallback _onTick;
+  /// will appear in the [toString] output in debug builds.
+  Ticker(this._onTick, { this.debugLabel }) {
+    assert(() {
+      _debugCreationStack = StackTrace.current;
+      return true;
+    });
+  }
 
   Completer<Null> _completer;
-  int _animationId;
+
-  Duration _startTime;
+  /// Whether this ticker has been silenced.
+  ///
+  /// While silenced, a ticker's clock can still run, but the callback will not
+  /// be called.
+  bool get muted => _muted;
+  bool _muted = false;
+  /// When set to true, silences the ticker, so that it is no longer ticking. If
+  /// a tick is already scheduled, it will unschedule it. This will not
+  /// unschedule the next frame, though.
+  ///
+  /// When set to false, unsilences the ticker, potentially scheduling a frame
+  /// to handle the next tick.
+  set muted(bool value) {
+    if (value == muted)
+      return;
+    _muted = value;
+    if (value) {
+      unscheduleTick();
+    } else if (shouldScheduleTick) {
+      scheduleTick();
+    }
+  }
 
   /// Whether this ticker has scheduled a call to call its callback
   /// on the next frame.
-  bool get isTicking => _completer != null;
-
-  /// Starts calling the ticker's callback once per animation frame.
   ///
-  /// The returned future resolves once the ticker stops ticking.
+  /// A ticker that is [muted] can be active (see [isActive]) yet not be
+  /// ticking. In that case, the ticker will not call its callback, and
+  /// [isTicking] will be false, but time will still be progressing.
+  // TODO(ianh): we should teach the scheduler binding about the lifecycle events
+  // and then this could return an accurate view of the actual scheduler.
+  bool get isTicking => _completer != null && !muted;
+
+  /// Whether time is elapsing for this ticker. Becomes true when [start] is
+  /// called and false when [stop] is called.
+  ///
+  /// A ticker can be active yet not be actually ticking (i.e. not be calling
+  /// the callback). To determine if a ticker is actually ticking, use
+  /// [isTicking].
+  bool get isActive => _completer != null;
+
+  Duration _startTime;
+
+  /// Starts the clock for this ticker. If the ticker is not [muted], then this
+  /// also starts calling the ticker's callback once per animation frame.
+  ///
+  /// The returned future resolves once the ticker [stop]s ticking.
+  ///
+  /// Calling this sets [isActive] to true.
+  ///
+  /// This method cannot be called while the ticker is active. To restart the
+  /// ticker, first [stop] it.
   Future<Null> start() {
-    assert(!isTicking);
+    assert(() {
+      if (isTicking) {
+        throw new FlutterError(
+          'A ticker was started twice.\n'
+          'A ticker that is already active cannot be started again without first stopping it.\n'
+          'The affected ticker was: ${ this.toString(debugIncludeStack: true) }'
+        );
+      }
+      return true;
+    });
     assert(_startTime == null);
     _completer = new Completer<Null>();
-    _scheduleTick();
+    if (shouldScheduleTick)
-    if (SchedulerBinding.instance.isProducingFrame)
+      scheduleTick();
+    if (SchedulerBinding.instance.schedulerPhase.index > SchedulerPhase.idle.index &&
+        SchedulerBinding.instance.schedulerPhase.index < SchedulerPhase.postFrameCallbacks.index)
       _startTime = SchedulerBinding.instance.currentFrameTimeStamp;
     return _completer.future;
   }
@@ -48,29 +128,49 @@ class Ticker {
   /// Stops calling the ticker's callback.
   ///
   /// Causes the future returned by [start] to resolve.
+  ///
+  /// Calling this sets [isActive] to false.
+  ///
+  /// This method does nothing if called when the ticker is inactive.
   void stop() {
     if (!isTicking)
       return;
 
-    _startTime = null;
-
-    if (_animationId != null) {
-      SchedulerBinding.instance.cancelFrameCallbackWithId(_animationId);
-      _animationId = null;
-    }
-
     // We take the _completer into a local variable so that isTicking is false
-    // when we actually complete the future (isTicking uses _completer
+    // when we actually complete the future (isTicking uses _completer to
-    // to determine its state).
+    // determine its state).
     Completer<Null> localCompleter = _completer;
     _completer = null;
+    _startTime = null;
     assert(!isTicking);
+
+    unscheduleTick();
     localCompleter.complete();
   }
 
+
+  final TickerCallback _onTick;
+
+  int _animationId;
+
+  /// Whether this ticker has already scheduled a frame callback.
+  @protected
+  bool get scheduled => _animationId != null;
+
+  /// Whether a tick should be scheduled.
+  ///
+  /// If this is true, then calling [scheduleTick] should succeed.
+  ///
+  /// Reasons why a tick should not be scheduled include:
+  ///
+  /// * A tick has already been scheduled for the coming frame.
+  /// * The ticker is not active ([start] has not been called).
+  /// * The ticker is not ticking, e.g. because it is [muted] (see [isTicking]).
+  bool get shouldScheduleTick => isTicking && !scheduled;
+
   void _tick(Duration timeStamp) {
     assert(isTicking);
-    assert(_animationId != null);
+    assert(scheduled);
     _animationId = null;
 
     if (_startTime == null)
@@ -78,14 +178,90 @@ class Ticker {
 
     _onTick(timeStamp - _startTime);
 
-    // The onTick callback may have scheduled another tick already.
+    // The onTick callback may have scheduled another tick already, for
-    if (isTicking && _animationId == null)
+    // example by calling stop then start again.
-      _scheduleTick(rescheduling: true);
+    if (shouldScheduleTick)
+      scheduleTick(rescheduling: true);
   }
 
-  void _scheduleTick({ bool rescheduling: false }) {
+  /// Schedules a tick for the next frame.
+  ///
+  /// This should only be called if [shouldScheduleTick] is true.
+  @protected
+  void scheduleTick({ bool rescheduling: false }) {
     assert(isTicking);
-    assert(_animationId == null);
+    assert(!scheduled);
+    assert(shouldScheduleTick);
     _animationId = SchedulerBinding.instance.scheduleFrameCallback(_tick, rescheduling: rescheduling);
   }
+
+  /// Cancels the frame callback that was requested by [scheduleTick], if any.
+  ///
+  /// Calling this method when no tick is [scheduled] is harmless.
+  ///
+  /// This method should not be called when [shouldScheduleTick] would return
+  /// true if no tick was scheduled.
+  @protected
+  void unscheduleTick() {
+    if (scheduled) {
+      SchedulerBinding.instance.cancelFrameCallbackWithId(_animationId);
+      _animationId = null;
+    }
+    assert(!shouldScheduleTick);
+  }
+
+  /// Makes this ticker take the state of another ticker, and disposes the other
+  /// ticker.
+  ///
+  /// This is useful if an object with a [Ticker] is given a new
+  /// [TickerProvider] but needs to maintain continuity. In particular, this
+  /// maintains the identity of the [Future] returned by the [start] function of
+  /// the original [Ticker] if the original ticker is active.
+  ///
+  /// This ticker must not be active when this method is called.
+  void absorbTicker(Ticker originalTicker) {
+    assert(!isTicking);
+    assert(_completer == null);
+    assert(_startTime == null);
+    assert(_animationId == null);
+    _completer = originalTicker._completer;
+    _startTime = originalTicker._startTime;
+    if (shouldScheduleTick)
+      scheduleTick();
+    originalTicker.dispose();
+  }
+
+  /// Release the resources used by this object. The object is no longer usable
+  /// after this method is called.
+  @mustCallSuper
+  void dispose() {
+    _completer = null;
+    // We intentionally don't null out _startTime. This means that if start()
+    // was ever called, the object is now in a bogus state. This weakly helps
+    // catch cases of use-after-dispose.
+    unscheduleTick();
+  }
+
+  final String debugLabel;
+  StackTrace _debugCreationStack;
+
+  @override
+  String toString({ bool debugIncludeStack: false }) {
+    final StringBuffer buffer = new StringBuffer();
+    buffer.write('$runtimeType(');
+    assert(() {
+      buffer.write(debugLabel ?? '');
+      return true;
+    });
+    buffer.write(')');
+    assert(() {
+      if (debugIncludeStack) {
+        buffer.writeln();
+        buffer.writeln('The stack trace when the $runtimeType was actually created was:');
+        FlutterError.defaultStackFilter(_debugCreationStack.toString().trimRight().split('\n')).forEach(buffer.writeln);
+      }
+      return true;
+    });
+    return buffer.toString();
+  }
 }

packages/flutter/lib/src/widgets/animated_cross_fade.dart

@@ -8,6 +8,7 @@ import 'package:meta/meta.dart';
 import 'animated_size.dart';
 import 'basic.dart';
 import 'framework.dart';
+import 'ticker_provider.dart';
 import 'transitions.dart';
 
 /// Specifies which of the children to show. See [AnimatedCrossFade].
@@ -80,7 +81,7 @@ class AnimatedCrossFade extends StatefulWidget {
   _AnimatedCrossFadeState createState() => new _AnimatedCrossFadeState();
 }
 
-class _AnimatedCrossFadeState extends State<AnimatedCrossFade> {
+class _AnimatedCrossFadeState extends State<AnimatedCrossFade> with TickerProviderStateMixin {
   _AnimatedCrossFadeState() : super();
 
   AnimationController _controller;
@@ -90,7 +91,7 @@ class _AnimatedCrossFadeState extends State<AnimatedCrossFade> {
   @override
   void initState() {
     super.initState();
-    _controller = new AnimationController(duration: config.duration);
+    _controller = new AnimationController(duration: config.duration, vsync: this);
     if (config.crossFadeState == CrossFadeState.showSecond)
       _controller.value = 1.0;
     _firstAnimation = _initAnimation(config.firstCurve, true);
@@ -185,6 +186,7 @@ class _AnimatedCrossFadeState extends State<AnimatedCrossFade> {
         alignment: FractionalOffset.topCenter,
         duration: config.duration,
         curve: config.sizeCurve,
+        vsync: this,
         child: new Stack(
           overflow: Overflow.visible,
           children: children

packages/flutter/lib/src/widgets/animated_size.dart

@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 import 'package:flutter/rendering.dart';
+import 'package:flutter/scheduler.dart';
 import 'package:meta/meta.dart';
 
 import 'basic.dart';
@@ -19,7 +20,8 @@ class AnimatedSize extends SingleChildRenderObjectWidget {
     Widget child,
     this.alignment: FractionalOffset.center,
     this.curve: Curves.linear,
-    @required this.duration
+    @required this.duration,
+    @required this.vsync,
   }) : super(key: key, child: child);
 
   /// The alignment of the child within the parent when the parent is not yet
@@ -42,12 +44,16 @@ class AnimatedSize extends SingleChildRenderObjectWidget {
   /// size.
   final Duration duration;
 
+  /// The [TickerProvider] for this widget.
+  final TickerProvider vsync;
+
   @override
   RenderAnimatedSize createRenderObject(BuildContext context) {
     return new RenderAnimatedSize(
       alignment: alignment,
       duration: duration,
-      curve: curve
+      curve: curve,
+      vsync: vsync,
     );
   }
 
@@ -57,6 +63,7 @@ class AnimatedSize extends SingleChildRenderObjectWidget {
     renderObject
       ..alignment = alignment
       ..duration = duration
-      ..curve = curve;
+      ..curve = curve
+      ..vsync = vsync;
   }
 }

packages/flutter/lib/src/widgets/dismissable.dart

@@ -5,9 +5,10 @@
 import 'package:meta/meta.dart';
 
 import 'basic.dart';
-import 'transitions.dart';
 import 'framework.dart';
 import 'gesture_detector.dart';
+import 'ticker_provider.dart';
+import 'transitions.dart';
 
 const Duration _kDismissDuration = const Duration(milliseconds: 200);
 const Curve _kResizeTimeCurve = const Interval(0.4, 1.0, curve: Curves.ease);
@@ -113,11 +114,11 @@ class Dismissable extends StatefulWidget {
   _DismissableState createState() => new _DismissableState();
 }
 
-class _DismissableState extends State<Dismissable> {
+class _DismissableState extends State<Dismissable> with TickerProviderStateMixin {
   @override
   void initState() {
     super.initState();
-    _moveController = new AnimationController(duration: _kDismissDuration)
+    _moveController = new AnimationController(duration: _kDismissDuration, vsync: this)
       ..addStatusListener(_handleDismissStatusChanged);
     _updateMoveAnimation();
   }
@@ -278,7 +279,7 @@ class _DismissableState extends State<Dismissable> {
       if (config.onDismissed != null)
         config.onDismissed(_dismissDirection);
     } else {
-      _resizeController = new AnimationController(duration: config.resizeDuration)
+      _resizeController = new AnimationController(duration: config.resizeDuration, vsync: this)
         ..addListener(_handleResizeProgressChanged);
       _resizeController.forward();
       setState(() {

packages/flutter/lib/src/widgets/editable.dart

@@ -405,9 +405,7 @@ class RawInputLineState extends ScrollableState<RawInputLine> {
       _keyboardHandle.release();
     if (_cursorTimer != null)
       _stopCursorTimer();
-    scheduleMicrotask(() { // can't hide while disposing, since it triggers a rebuild
+    _selectionOverlay?.dispose();
-      _selectionOverlay?.dispose();
-    });
     super.dispose();
   }
 
@@ -432,14 +430,12 @@ class RawInputLineState extends ScrollableState<RawInputLine> {
       _stopCursorTimer();
 
     if (_selectionOverlay != null) {
-      scheduleMicrotask(() { // can't update while disposing, since it triggers a rebuild
+      if (focused) {
-        if (focused) {
+        _selectionOverlay.update(config.value);
-          _selectionOverlay.update(config.value);
+      } else {
-        } else {
+        _selectionOverlay?.dispose();
-          _selectionOverlay?.hide();
+        _selectionOverlay = null;
-          _selectionOverlay = null;
+      }
-        }
-      });
     }
 
     return new _EditableLineWidget(

packages/flutter/lib/src/widgets/framework.dart

@@ -1207,21 +1207,23 @@ class _InactiveElements {
       }
       return true;
     });
-    element.unmount();
-    assert(element._debugLifecycleState == _ElementLifecycle.defunct);
     element.visitChildren((Element child) {
       assert(child._parent == element);
       _unmount(child);
     });
+    element.unmount();
+    assert(element._debugLifecycleState == _ElementLifecycle.defunct);
   }
 
   void _unmountAll() {
+    _locked = true;
+    final List<Element> elements = _elements.toList()..sort(Element._sort);
+    _elements.clear();
     try {
-      _locked = true;
+      for (Element element in elements.reversed)
-      for (Element element in _elements)
         _unmount(element);
     } finally {
-      _elements.clear();
+      assert(_elements.isEmpty);
       _locked = false;
     }
   }
@@ -1365,7 +1367,8 @@ abstract class BuildContext {
   /// [State.initState] methods, because those methods would not get called
   /// again if the inherited value were to change. To ensure that the widget
   /// correctly updates itself when the inherited value changes, only call this
-  /// (directly or indirectly) from build methods or layout and paint callbacks.
+  /// (directly or indirectly) from build methods, layout and paint callbacks, or
+  /// from [State.dependenciesChanged].
   ///
   /// It is also possible to call this from interaction event handlers (e.g.
   /// gesture callbacks) or timers, to obtain a value once, if that value is not
@@ -1373,6 +1376,12 @@ abstract class BuildContext {
   ///
   /// Calling this method is O(1) with a small constant factor, but will lead to
   /// the widget being rebuilt more often.
+  ///
+  /// Once a widget registers a dependency on a particular type by calling this
+  /// method, it will be rebuilt, and [State.dependenciesChanged] will be
+  /// called, whenever changes occur relating to that widget until the next time
+  /// the widget or one of its ancestors is moved (for example, because an
+  /// ancestor is added or removed).
   InheritedWidget inheritFromWidgetOfExactType(Type targetType);
 
   /// Returns the nearest ancestor widget of the given type, which must be the
@@ -1647,7 +1656,7 @@ class BuildOwner {
           });
         }
       }
-      _dirtyElements.sort(_elementSort);
+      _dirtyElements.sort(Element._sort);
       _dirtyElementsNeedsResorting = false;
       int dirtyCount = _dirtyElements.length;
       int index = 0;
@@ -1668,7 +1677,7 @@ class BuildOwner {
         }
         index += 1;
         if (dirtyCount < _dirtyElements.length || _dirtyElementsNeedsResorting) {
-          _dirtyElements.sort(_elementSort);
+          _dirtyElements.sort(Element._sort);
           _dirtyElementsNeedsResorting = false;
           dirtyCount = _dirtyElements.length;
           while (index > 0 && _dirtyElements[index - 1].dirty) {
@@ -1715,18 +1724,6 @@ class BuildOwner {
     assert(_debugStateLockLevel >= 0);
   }
 
-  static int _elementSort(BuildableElement a, BuildableElement b) {
-    if (a.depth < b.depth)
-      return -1;
-    if (b.depth < a.depth)
-      return 1;
-    if (b.dirty && !a.dirty)
-      return -1;
-    if (a.dirty && !b.dirty)
-      return 1;
-    return 0;
-  }
-
   /// Complete the element build pass by unmounting any elements that are no
   /// longer active.
   ///
@@ -1837,6 +1834,18 @@ abstract class Element implements BuildContext {
   int get depth => _depth;
   int _depth;
 
+  static int _sort(BuildableElement a, BuildableElement b) {
+    if (a.depth < b.depth)
+      return -1;
+    if (b.depth < a.depth)
+      return 1;
+    if (b.dirty && !a.dirty)
+      return -1;
+    if (a.dirty && !b.dirty)
+      return 1;
+    return 0;
+  }
+
   /// The configuration for this element.
   @override
   Widget get widget => _widget;
@@ -2206,6 +2215,7 @@ abstract class Element implements BuildContext {
     // We unregistered our dependencies in deactivate, but never cleared the list.
     // Since we're going to be reused, let's clear our list now.
     _dependencies?.clear();
+    _hadUnsatisfiedDependencies = false;
     _updateInheritance();
     assert(() { _debugLifecycleState = _ElementLifecycle.active; return true; });
   }
@@ -2554,19 +2564,6 @@ abstract class BuildableElement extends Element {
       owner._debugCurrentBuildTarget = this;
      return true;
     });
-    _hadUnsatisfiedDependencies = false;
-    // In theory, we would also clear our actual _dependencies here. However, to
-    // clear it we'd have to notify each of them, unregister from them, and then
-    // reregister as soon as the build function re-dependended on it. So to
-    // avoid faffing around we just never unregister our dependencies except
-    // when we're deactivated. In principle this means we might be getting
-    // notified about widget types we once inherited from but no longer do, but
-    // in practice this is so rare that the extra cost when it does happen is
-    // far outweighed by the avoided work in the common case.
-    // We _do_ clear the list properly any time our ancestor chain changes in a
-    // way that might result in us getting a different Element's Widget for a
-    // particular Type. This avoids the potential of being registered to
-    // multiple identically-typed Widgets' Elements at the same time.
     performRebuild();
     assert(() {
       assert(owner._debugCurrentBuildTarget == this);

packages/flutter/lib/src/widgets/implicit_animations.dart

@@ -9,6 +9,7 @@ import 'basic.dart';
 import 'container.dart';
 import 'framework.dart';
 import 'text.dart';
+import 'ticker_provider.dart';
 
 /// An interpolation between two [BoxConstraint]s.
 class BoxConstraintsTween extends Tween<BoxConstraints> {
@@ -114,7 +115,7 @@ typedef Tween<T> TweenConstructor<T>(T targetValue);
 typedef Tween<T> TweenVisitor<T>(Tween<T> tween, T targetValue, TweenConstructor<T> constructor);
 
 /// A base class for widgets with implicit animations.
-abstract class AnimatedWidgetBaseState<T extends ImplicitlyAnimatedWidget> extends State<T> {
+abstract class AnimatedWidgetBaseState<T extends ImplicitlyAnimatedWidget> extends State<T> with SingleTickerProviderStateMixin {
   AnimationController _controller;
 
   /// The animation driving this widget's implicit animations.
@@ -126,7 +127,8 @@ abstract class AnimatedWidgetBaseState<T extends ImplicitlyAnimatedWidget> exten
     super.initState();
     _controller = new AnimationController(
       duration: config.duration,
-      debugLabel: '${config.toStringShort()}'
+      debugLabel: '${config.toStringShort()}',
+      vsync: this,
     )..addListener(_handleAnimationChanged);
     _updateCurve();
     _constructTweens();

packages/flutter/lib/src/widgets/mimic.dart

@@ -28,14 +28,16 @@ class MimicableHandle {
 
 /// An overlay entry that is mimicking another widget.
 class MimicOverlayEntry {
-  MimicOverlayEntry._(this._handle) {
+  MimicOverlayEntry._(this._handle, this._overlay) {
-    _overlayEntry = new OverlayEntry(builder: _build);
     _initialGlobalBounds = _handle.globalBounds;
+    _overlayEntry = new OverlayEntry(builder: _build);
+    _overlay.insert(_overlayEntry);
   }
 
   Rect _initialGlobalBounds;
 
   MimicableHandle _handle;
+  OverlayState _overlay;
   OverlayEntry _overlayEntry;
 
   // Animation state
@@ -63,7 +65,8 @@ class MimicOverlayEntry {
     _curve = curve;
     // TODO(abarth): Support changing the animation target when in flight.
     assert(_controller == null);
-    _controller = new AnimationController(duration: duration)
+    // TODO(ianh): Need to get a TickerProvider that's tied to the Overlay's TickerMode.
+    _controller = new AnimationController(duration: duration, vsync: _overlay)
       ..addListener(_overlayEntry.markNeedsBuild);
     return _controller.forward();
   }
@@ -214,9 +217,7 @@ class MimicableState extends State<Mimicable> {
   /// placed in the enclosing overlay.
   MimicOverlayEntry liftToOverlay() {
     OverlayState overlay = Overlay.of(context, debugRequiredFor: config);
-    MimicOverlayEntry entry = new MimicOverlayEntry._(startMimic());
+    return new MimicOverlayEntry._(startMimic(), overlay);
-    overlay.insert(entry._overlayEntry);
-    return entry;
   }
 
   void _stopMimic() {

packages/flutter/lib/src/widgets/navigator.dart

@@ -10,6 +10,7 @@ import 'binding.dart';
 import 'focus.dart';
 import 'framework.dart';
 import 'overlay.dart';
+import 'ticker_provider.dart';
 
 /// An abstraction for an entry managed by a [Navigator].
 ///
@@ -325,7 +326,7 @@ class Navigator extends StatefulWidget {
 }
 
 /// The state for a [Navigator] widget.
-class NavigatorState extends State<Navigator> {
+class NavigatorState extends State<Navigator> with TickerProviderStateMixin {
   final GlobalKey<OverlayState> _overlayKey = new GlobalKey<OverlayState>();
   final List<Route<dynamic>> _history = new List<Route<dynamic>>();
 

packages/flutter/lib/src/widgets/overlay.dart

@@ -2,14 +2,17 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'dart:async';
 import 'dart:collection';
 
-import 'package:meta/meta.dart';
 import 'package:flutter/rendering.dart';
+import 'package:flutter/scheduler.dart';
+import 'package:meta/meta.dart';
 
 import 'basic.dart';
 import 'debug.dart';
 import 'framework.dart';
+import 'ticker_provider.dart';
 
 /// A place in an [Overlay] that can contain a widget.
 ///
@@ -116,9 +119,27 @@ class OverlayEntry {
   final GlobalKey<_OverlayEntryState> _key = new GlobalKey<_OverlayEntryState>();
 
   /// Remove this entry from the overlay.
+  ///
+  /// This should only be called once.
+  ///
+  /// If this method is called while the [SchedulerBinding.schedulerPhase] is
+  /// [SchedulerBinding.persistentCallbacks], i.e. during the build, layout, or
+  /// paint phases (see [WidgetsBinding.beginFrame]), then the removal is
+  /// delayed until the post-frame callbacks phase. Otherwise the removal is
+  /// done synchronously. This means that it is safe to call during builds, but
+  /// also that if you do call this during a build, the UI will not update until
+  /// the next frame (i.e. many milliseconds later).
   void remove() {
-    _overlay?._remove(this);
+    assert(_overlay != null);
+    OverlayState overlay = _overlay;
     _overlay = null;
+    if (SchedulerBinding.instance.schedulerPhase == SchedulerPhase.persistentCallbacks) {
+      SchedulerBinding.instance.addPostFrameCallback((Duration duration) {
+        overlay._remove(this);
+      });
+    } else {
+      overlay._remove(this);
+    }
   }
 
   /// Cause this entry to rebuild during the next pipeline flush.
@@ -226,7 +247,7 @@ class Overlay extends StatefulWidget {
 ///
 /// Used to insert [OverlayEntry]s into the overlay using the [insert] and
 /// [insertAll] functions.
-class OverlayState extends State<Overlay> {
+class OverlayState extends State<Overlay> with TickerProviderStateMixin {
   final List<OverlayEntry> _entries = new List<OverlayEntry>();
 
   @override
@@ -268,9 +289,10 @@ class OverlayState extends State<Overlay> {
   }
 
   void _remove(OverlayEntry entry) {
-    _entries.remove(entry);
+    if (mounted) {
-    if (mounted)
+      _entries.remove(entry);
       setState(() { /* entry was removed */ });
+    }
   }
 
   /// (DEBUG ONLY) Check whether a given entry is visible (i.e., not behind an
@@ -319,7 +341,7 @@ class OverlayState extends State<Overlay> {
         if (entry.opaque)
           onstage = false;
       } else if (entry.maintainState) {
-        offstageChildren.add(new _OverlayEntry(entry));
+        offstageChildren.add(new TickerMode(enabled: false, child: new _OverlayEntry(entry)));
       }
     }
     return new _Theatre(

packages/flutter/lib/src/widgets/routes.dart

@@ -122,7 +122,11 @@ abstract class TransitionRoute<T> extends OverlayRoute<T> {
   AnimationController createAnimationController() {
     Duration duration = transitionDuration;
     assert(duration != null && duration >= Duration.ZERO);
-    return new AnimationController(duration: duration, debugLabel: debugLabel);
+    return new AnimationController(
+      duration: duration,
+      debugLabel: debugLabel,
+      vsync: navigator,
+    );
   }
 
   /// Called to create the animation that exposes the current progress of

packages/flutter/lib/src/widgets/scrollable.dart

@@ -18,6 +18,7 @@ import 'notification_listener.dart';
 import 'page_storage.dart';
 import 'scroll_behavior.dart';
 import 'scroll_configuration.dart';
+import 'ticker_provider.dart';
 
 /// Identifies one or both limits of a [Scrollable] in terms of its scrollDirection.
 enum ScrollableEdge {
@@ -262,11 +263,11 @@ class Scrollable extends StatefulWidget {
 /// terms of the [pixelOffsetToScrollOffset] and
 /// [scrollOffsetToPixelOffset] methods.
 @optionalTypeArgs
-class ScrollableState<T extends Scrollable> extends State<T> {
+class ScrollableState<T extends Scrollable> extends State<T> with SingleTickerProviderStateMixin {
   @override
   void initState() {
     super.initState();
-    _controller = new AnimationController.unbounded()
+    _controller = new AnimationController.unbounded(vsync: this)
       ..addListener(_handleAnimationChanged)
       ..addStatusListener(_handleAnimationStatusChanged);
     _scrollOffset = PageStorage.of(context)?.readState(context) ?? config.initialScrollOffset ?? 0.0;

packages/flutter/lib/src/widgets/text_selection.dart

@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 import 'package:flutter/rendering.dart';
+import 'package:flutter/scheduler.dart';
 import 'package:meta/meta.dart';
 
 import 'basic.dart';
@@ -82,6 +83,10 @@ class TextSelectionOverlay implements TextSelectionDelegate {
     this.toolbarBuilder
   }): _input = input {
     assert(context != null);
+    final OverlayState overlay = Overlay.of(context);
+    assert(overlay != null);
+    _handleController = new AnimationController(duration: _kFadeDuration, vsync: overlay);
+    _toolbarController = new AnimationController(duration: _kFadeDuration, vsync: overlay);
   }
 
   /// The context in which the selection handles should appear.
@@ -117,8 +122,8 @@ class TextSelectionOverlay implements TextSelectionDelegate {
 
   /// Controls the fade-in animations.
   static const Duration _kFadeDuration = const Duration(milliseconds: 150);
-  final AnimationController _handleController = new AnimationController(duration: _kFadeDuration);
+  AnimationController _handleController;
-  final AnimationController _toolbarController = new AnimationController(duration: _kFadeDuration);
+  AnimationController _toolbarController;
   Animation<double> get _handleOpacity => _handleController.view;
   Animation<double> get _toolbarOpacity => _toolbarController.view;
 
@@ -153,11 +158,26 @@ class TextSelectionOverlay implements TextSelectionDelegate {
   }
 
   /// Updates the overlay after the [selection] has changed.
+  ///
+  /// If this method is called while the [SchedulerBinding.schedulerPhase] is
+  /// [SchedulerBinding.persistentCallbacks], i.e. during the build, layout, or
+  /// paint phases (see [WidgetsBinding.beginFrame]), then the update is delayed
+  /// until the post-frame callbacks phase. Otherwise the update is done
+  /// synchronously. This means that it is safe to call during builds, but also
+  /// that if you do call this during a build, the UI will not update until the
+  /// next frame (i.e. many milliseconds later).
   void update(InputValue newInput) {
     if (_input == newInput)
       return;
-
     _input = newInput;
+    if (SchedulerBinding.instance.schedulerPhase == SchedulerPhase.persistentCallbacks) {
+      SchedulerBinding.instance.addPostFrameCallback(_markNeedsBuild);
+    } else {
+      _markNeedsBuild();
+    }
+  }
+
+  void _markNeedsBuild([Duration duration]) {
     if (_handles != null) {
       _handles[0].markNeedsBuild();
       _handles[1].markNeedsBuild();

packages/flutter/lib/src/widgets/ticker_provider.dart

@@ -0,0 +1,220 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/foundation.dart';
+import 'package:flutter/scheduler.dart';
+import 'package:meta/meta.dart';
+
+import 'framework.dart';
+
+export 'package:flutter/scheduler.dart' show TickerProvider;
+
+/// Enables or disables tickers (and thus animation controllers) in the widget
+/// subtree.
+///
+/// This only works if [AnimationController] objects are created using
+/// widget-aware ticker providers. For example, using a
+/// [TickerProviderStateMixin] or a [SingleTickerProviderStateMixin].
+class TickerMode extends InheritedWidget {
+  /// Creates a widget that enables or disables tickers.
+  ///
+  /// The [enabled] argument must not be null.
+  TickerMode({
+    Key key,
+    @required this.enabled,
+    Widget child
+  }) : super(key: key, child: child) {
+    assert(enabled != null);
+  }
+
+  /// The current ticker mode of this subtree.
+  ///
+  /// If true, then tickers in this subtree will tick.
+  ///
+  /// If false, then tickers in this subtree will not tick. Animations driven by
+  /// such tickers are not paused, they just don't call their callbacks. Time
+  /// still elapses.
+  final bool enabled;
+
+  /// Whether tickers in the given subtree should be enabled or disabled.
+  ///
+  /// This is used automatically by [TickerProviderStateMixin] and
+  /// [SingleTickerProviderStateMixin] to decide if their tickers should be
+  /// enabled or disabled.
+  ///
+  /// In the absence of a [TickerMode] widget, this function defaults to true.
+  static bool of(BuildContext context) {
+    TickerMode widget = context.inheritFromWidgetOfExactType(TickerMode);
+    return widget?.enabled ?? true;
+  }
+
+  @override
+  bool updateShouldNotify(TickerMode old) => enabled != old.enabled;
+
+  @override
+  void debugFillDescription(List<String> description) {
+    super.debugFillDescription(description);
+    description.add('mode: ${ enabled ? "enabled" : "disabled" }');
+  }
+}
+
+/// Provides a single [Ticker] that is configured to only tick while the current
+/// tree is enabled, as defined by [TickerMode].
+///
+/// To create the [AnimationController] in a [State] that only uses a single
+/// [AnimationController], mix in this class, then pass `vsync: this`
+/// to the animation controller constructor.
+///
+/// This mixin only supports vending a single ticker. If you might have multiple
+/// [AnimationController] objects over the lifetime of the [State], use a full
+/// [TickerProviderStateMixin] instead.
+abstract class SingleTickerProviderStateMixin implements State<dynamic>, TickerProvider { // ignore: TYPE_ARGUMENT_NOT_MATCHING_BOUNDS, https://github.com/dart-lang/sdk/issues/25232
+
+  Ticker _ticker;
+
+  @override
+  Ticker createTicker(TickerCallback onTick) {
+    assert(() {
+      if (_ticker == null)
+        return true;
+      throw new FlutterError(
+        '$runtimeType is a SingleTickerProviderStateMixin but multiple tickers were created.\n'
+        'A SingleTickerProviderStateMixin can only be used as a TickerProvider once. If a '
+        'State is used for multiple AnimationController objects, or if it is passed to other '
+        'objects and those objects might use it more than one time in total, then instead of '
+        'mixing in a SingleTickerProviderStateMixin, use a regular TickerProviderStateMixin.'
+      );
+    });
+    _ticker = new Ticker(onTick, debugLabel: 'created by $this');
+    return _ticker;
+  }
+
+  @override
+  void dispose() {
+    assert(() {
+      if (_ticker == null || !_ticker.isActive)
+        return true;
+      throw new FlutterError(
+        '$this was disposed with an active Ticker.\n'
+        '$runtimeType created a Ticker via its SingleTickerProviderStateMixin, but at the time '
+        'dispose() was called on the mixin, that Ticker was still active. The Ticker must '
+        'be disposed before calling super.dispose(). Tickers used by AnimationControllers '
+        'should be disposed by calling dispose() on the AnimationController itself. '
+        'Otherwise, the ticker will leak.\n'
+        'The offending ticker was: ${_ticker.toString(debugIncludeStack: true)}'
+      );
+    });
+    super.dispose();
+  }
+
+  @override
+  void dependenciesChanged() {
+    _ticker.muted = !TickerMode.of(context);
+    super.dependenciesChanged();
+  }
+
+  @override
+  void debugFillDescription(List<String> description) {
+    super.debugFillDescription(description);
+    if (_ticker != null) {
+      if (_ticker.isActive && _ticker.muted)
+        description.add('ticker active but muted');
+      else
+      if (_ticker.isActive)
+        description.add('ticker active');
+      else
+      if (_ticker.muted)
+        description.add('ticker inactive and muted');
+      else
+        description.add('ticker inactive');
+    }
+  }
+
+}
+
+/// Provides [Ticker] objects that are configured to only tick while the current
+/// tree is enabled, as defined by [TickerMode].
+///
+/// To create an [AnimationController] in a class that uses this mixin, pass
+/// `vsync: this` to the animation controller constructor whenever you
+/// create a new animation controller.
+///
+/// If you only have a single [Ticker] (for example only a single
+/// [AnimationController]) for the lifetime of your [State], then using a
+/// [SingleTickerProviderStateMixin] is more efficient. This is the common case.
+abstract class TickerProviderStateMixin implements State<dynamic>, TickerProvider { // ignore: TYPE_ARGUMENT_NOT_MATCHING_BOUNDS, https://github.com/dart-lang/sdk/issues/25232
+
+  Set<Ticker> _tickers;
+
+  @override
+  Ticker createTicker(TickerCallback onTick) {
+    _tickers ??= new Set<_WidgetTicker>();
+    final _WidgetTicker result = new _WidgetTicker(onTick, this, debugLabel: 'created by $this');
+    _tickers.add(result);
+    return result;
+  }
+
+  void _removeTicker(_WidgetTicker ticker) {
+    assert(_tickers != null);
+    assert(_tickers.contains(ticker));
+    _tickers.remove(ticker);
+  }
+
+  @override
+  void dispose() {
+    assert(() {
+      if (_tickers != null) {
+        for (Ticker ticker in _tickers) {
+          if (ticker.isActive) {
+            throw new FlutterError(
+              '$this was disposed with an active Ticker.\n'
+              '$runtimeType created a Ticker via its TickerProviderStateMixin, but at the time '
+              'dispose() was called on the mixin, that Ticker was still active. All Tickers must '
+              'be disposed before calling super.dispose(). Tickers used by AnimationControllers '
+              'should be disposed by calling dispose() on the AnimationController itself. '
+              'Otherwise, the ticker will leak.\n'
+              'The offending ticker was: ${ticker.toString(debugIncludeStack: true)}'
+            );
+          }
+        }
+      }
+      return true;
+    });
+    super.dispose();
+  }
+
+  @override
+  void dependenciesChanged() {
+    final bool muted = !TickerMode.of(context);
+    if (_tickers != null) {
+      for (Ticker ticker in _tickers)
+        ticker.muted = muted;
+    }
+    super.dependenciesChanged();
+  }
+
+  @override
+  void debugFillDescription(List<String> description) {
+    super.debugFillDescription(description);
+    if (_tickers != null)
+      description.add('tracking ${_tickers.length} ticker${_tickers.length == 1 ? "" : "s"}');
+  }
+
+}
+
+// This class should really be called _DisposingTicker or some such, but this
+// class name leaks into stack traces and error messages and that name would be
+// confusing. Instead we use the less precise but more anodyne "_WidgetTicker",
+// which attracts less attention.
+class _WidgetTicker extends Ticker {
+  _WidgetTicker(TickerCallback onTick, this._creator, { String debugLabel }) : super(onTick, debugLabel: debugLabel);
+
+  final TickerProviderStateMixin _creator;
+
+  @override
+  void dispose() {
+    _creator._removeTicker(this);
+    super.dispose();
+  }
+}

packages/flutter/lib/widgets.dart

@@ -48,15 +48,16 @@ export 'src/widgets/raw_keyboard_listener.dart';
 export 'src/widgets/routes.dart';
 export 'src/widgets/scroll_behavior.dart';
 export 'src/widgets/scroll_configuration.dart';
+export 'src/widgets/scrollable.dart';
 export 'src/widgets/scrollable_grid.dart';
 export 'src/widgets/scrollable_list.dart';
-export 'src/widgets/scrollable.dart';
 export 'src/widgets/semantics_debugger.dart';
 export 'src/widgets/size_changed_layout_notifier.dart';
 export 'src/widgets/status_transitions.dart';
 export 'src/widgets/table.dart';
-export 'src/widgets/text_selection.dart';
 export 'src/widgets/text.dart';
+export 'src/widgets/text_selection.dart';
+export 'src/widgets/ticker_provider.dart';
 export 'src/widgets/title.dart';
 export 'src/widgets/transitions.dart';
 export 'src/widgets/unique_widget.dart';

packages/flutter/test/animation/animation_controller_test.dart

@@ -6,6 +6,8 @@ import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/animation.dart';
 import 'package:flutter/widgets.dart';
 
+import 'animation_tester.dart';
+
 void main() {
   setUp(() {
     WidgetsFlutterBinding.ensureInitialized();
@@ -14,7 +16,8 @@ void main() {
 
   test('Can set value during status callback', () {
     AnimationController controller = new AnimationController(
-      duration: const Duration(milliseconds: 100)
+      duration: const Duration(milliseconds: 100),
+      vsync: const TestVSync(),
     );
     bool didComplete = false;
     bool didDismiss = false;
@@ -45,7 +48,8 @@ void main() {
 
   test('Receives status callbacks for forward and reverse', () {
     AnimationController controller = new AnimationController(
-      duration: const Duration(milliseconds: 100)
+      duration: const Duration(milliseconds: 100),
+      vsync: const TestVSync(),
     );
     List<double> valueLog = <double>[];
     List<AnimationStatus> log = <AnimationStatus>[];
@@ -107,7 +111,8 @@ void main() {
 
   test('Forward and reverse from values', () {
     AnimationController controller = new AnimationController(
-      duration: const Duration(milliseconds: 100)
+      duration: const Duration(milliseconds: 100),
+      vsync: const TestVSync(),
     );
     List<double> valueLog = <double>[];
     List<AnimationStatus> statusLog = <AnimationStatus>[];
@@ -134,7 +139,8 @@ void main() {
 
   test('Forward only from value', () {
     AnimationController controller = new AnimationController(
-      duration: const Duration(milliseconds: 100)
+      duration: const Duration(milliseconds: 100),
+      vsync: const TestVSync(),
     );
     List<double> valueLog = <double>[];
     List<AnimationStatus> statusLog = <AnimationStatus>[];
@@ -154,7 +160,8 @@ void main() {
 
   test('Can fling to upper and lower bounds', () {
     AnimationController controller = new AnimationController(
-      duration: const Duration(milliseconds: 100)
+      duration: const Duration(milliseconds: 100),
+      vsync: const TestVSync(),
     );
 
     controller.fling();
@@ -166,7 +173,8 @@ void main() {
     AnimationController largeRangeController = new AnimationController(
       duration: const Duration(milliseconds: 100),
       lowerBound: -30.0,
-      upperBound: 45.0
+      upperBound: 45.0,
+      vsync: const TestVSync(),
     );
 
     largeRangeController.fling();
@@ -182,7 +190,8 @@ void main() {
 
   test('lastElapsedDuration control test', () {
     AnimationController controller = new AnimationController(
-      duration: const Duration(milliseconds: 100)
+      duration: const Duration(milliseconds: 100),
+      vsync: const TestVSync(),
     );
     controller.forward();
     WidgetsBinding.instance.handleBeginFrame(const Duration(milliseconds: 20));
@@ -194,7 +203,8 @@ void main() {
 
   test('toString control test', () {
     AnimationController controller = new AnimationController(
-      duration: const Duration(milliseconds: 100)
+      duration: const Duration(milliseconds: 100),
+      vsync: const TestVSync(),
     );
     expect(controller.toString(), hasOneLineDescription);
     controller.forward();

packages/flutter/test/animation/animation_tester.dart

@@ -0,0 +1,12 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/scheduler.dart';
+
+class TestVSync implements TickerProvider {
+  const TestVSync();
+
+  @override
+  Ticker createTicker(TickerCallback onTick) => new Ticker(onTick);
+}

packages/flutter/test/animation/animations_test.dart

@@ -6,6 +6,8 @@ import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/animation.dart';
 import 'package:flutter/widgets.dart';
 
+import 'animation_tester.dart';
+
 void main() {
   setUp(() {
     WidgetsFlutterBinding.ensureInitialized();
@@ -24,7 +26,8 @@ void main() {
     curvedAnimation.reverseCurve = Curves.elasticOut;
     expect(curvedAnimation.toString(), hasOneLineDescription);
     AnimationController controller = new AnimationController(
-      duration: const Duration(milliseconds: 500)
+      duration: const Duration(milliseconds: 500),
+      vsync: const TestVSync(),
     );
     controller
       ..value = 0.5
@@ -48,7 +51,9 @@ void main() {
   });
 
   test('ProxyAnimation set parent generates value changed', () {
-    AnimationController controller = new AnimationController();
+    AnimationController controller = new AnimationController(
+      vsync: const TestVSync(),
+    );
     controller.value = 0.5;
     bool didReceiveCallback = false;
     ProxyAnimation animation = new ProxyAnimation()
@@ -65,7 +70,9 @@ void main() {
   });
 
   test('ReverseAnimation calls listeners', () {
-    AnimationController controller = new AnimationController();
+    AnimationController controller = new AnimationController(
+      vsync: const TestVSync(),
+    );
     controller.value = 0.5;
     bool didReceiveCallback = false;
     void listener() {
@@ -85,8 +92,12 @@ void main() {
   });
 
   test('TrainHoppingAnimation', () {
-    AnimationController currentTrain = new AnimationController();
+    AnimationController currentTrain = new AnimationController(
-    AnimationController nextTrain = new AnimationController();
+      vsync: const TestVSync(),
+    );
+    AnimationController nextTrain = new AnimationController(
+      vsync: const TestVSync(),
+    );
     currentTrain.value = 0.5;
     nextTrain.value = 0.75;
     bool didSwitchTrains = false;

packages/flutter/test/animation/tween_test.dart

@@ -6,19 +6,25 @@ import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/animation.dart';
 import 'package:flutter/widgets.dart';
 
+import 'animation_tester.dart';
+
 void main() {
   test('Can chain tweens', () {
     Tween<double> tween = new Tween<double>(begin: 0.30, end: 0.50);
     expect(tween, hasOneLineDescription);
     Animatable<double> chain = tween.chain(new Tween<double>(begin: 0.50, end: 1.0));
-    AnimationController controller = new AnimationController();
+    AnimationController controller = new AnimationController(
+      vsync: const TestVSync(),
+    );
     expect(chain.evaluate(controller), 0.40);
     expect(chain, hasOneLineDescription);
   });
 
   test('Can animated tweens', () {
     Tween<double> tween = new Tween<double>(begin: 0.30, end: 0.50);
-    AnimationController controller = new AnimationController();
+    AnimationController controller = new AnimationController(
+      vsync: const TestVSync(),
+    );
     Animation<double> animation = tween.animate(controller);
     controller.value = 0.50;
     expect(animation.value, 0.40);

packages/flutter/test/widget/animated_size_test.dart

@@ -21,6 +21,7 @@ void main() {
       new Center(
         child: new AnimatedSize(
           duration: const Duration(milliseconds: 200),
+          vsync: tester,
           child: new SizedBox(
             width: 100.0,
             height: 100.0
@@ -37,6 +38,7 @@ void main() {
       new Center(
         child: new AnimatedSize(
           duration: new Duration(milliseconds: 200),
+          vsync: tester,
           child: new SizedBox(
             width: 200.0,
             height: 200.0
@@ -63,6 +65,7 @@ void main() {
       new Center(
         child: new AnimatedSize(
           duration: new Duration(milliseconds: 200),
+          vsync: tester,
           child: new SizedBox(
             width: 100.0,
             height: 100.0
@@ -94,6 +97,7 @@ void main() {
           height: 100.0,
           child: new AnimatedSize(
             duration: const Duration(milliseconds: 200),
+            vsync: tester,
             child: new SizedBox(
               width: 100.0,
               height: 100.0
@@ -114,6 +118,7 @@ void main() {
           height: 100.0,
           child: new AnimatedSize(
             duration: const Duration(milliseconds: 200),
+            vsync: tester,
             child: new SizedBox(
               width: 200.0,
               height: 200.0
@@ -134,6 +139,7 @@ void main() {
       new Center(
         child: new AnimatedSize(
           duration: const Duration(milliseconds: 200),
+          vsync: tester,
           child: new AnimatedContainer(
             duration: const Duration(milliseconds: 100),
             width: 100.0,
@@ -151,6 +157,7 @@ void main() {
       new Center(
         child: new AnimatedSize(
           duration: const Duration(milliseconds: 200),
+          vsync: tester,
           child: new AnimatedContainer(
             duration: const Duration(milliseconds: 100),
             width: 200.0,

packages/flutter/test/widget/flow_test.dart

@@ -32,7 +32,9 @@ class TestFlowDelegate extends FlowDelegate {
 
 void main() {
   testWidgets('Flow control test', (WidgetTester tester) async {
-    AnimationController startOffset = new AnimationController.unbounded();
+    AnimationController startOffset = new AnimationController.unbounded(
+      vsync: tester,
+    );
     List<int> log = <int>[];
 
     Widget buildBox(int i) {

packages/flutter/test/widget/positioned_test.dart

@@ -23,7 +23,8 @@ void main() {
       )
     );
     final AnimationController controller = new AnimationController(
-      duration: const Duration(seconds: 10)
+      duration: const Duration(seconds: 10),
+      vsync: tester,
     );
     final List<Size> sizes = <Size>[];
     final List<Offset> positions = <Offset>[];

packages/flutter/test/widget/ticker_provider_test.dart

@@ -0,0 +1,53 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter_test/flutter_test.dart';
+import 'package:flutter/material.dart';
+
+void main() {
+  testWidgets('TickerMode', (WidgetTester tester) async {
+    await tester.pumpWidget(new TickerMode(
+      enabled: false,
+      child: new LinearProgressIndicator()
+    ));
+
+    expect(tester.binding.transientCallbackCount, 0);
+
+    await tester.pumpWidget(new TickerMode(
+      enabled: true,
+      child: new LinearProgressIndicator()
+    ));
+
+    expect(tester.binding.transientCallbackCount, 1);
+
+    await tester.pumpWidget(new TickerMode(
+      enabled: false,
+      child: new LinearProgressIndicator()
+    ));
+
+    expect(tester.binding.transientCallbackCount, 0);
+  });
+
+  testWidgets('Navigation with TickerMode', (WidgetTester tester) async {
+    await tester.pumpWidget(new MaterialApp(
+      home: new LinearProgressIndicator(),
+      routes: <String, WidgetBuilder>{
+        '/test': (BuildContext context) => new Text('hello'),
+      },
+    ));
+    expect(tester.binding.transientCallbackCount, 1);
+    tester.state/*<NavigatorState>*/(find.byType(Navigator)).pushNamed('/test');
+    expect(tester.binding.transientCallbackCount, 2);
+    await tester.pump();
+    expect(tester.binding.transientCallbackCount, 2);
+    await tester.pump(const Duration(seconds: 5));
+    expect(tester.binding.transientCallbackCount, 0);
+    tester.state/*<NavigatorState>*/(find.byType(Navigator)).pop();
+    expect(tester.binding.transientCallbackCount, 1);
+    await tester.pump();
+    expect(tester.binding.transientCallbackCount, 2);
+    await tester.pump(const Duration(seconds: 5));
+    expect(tester.binding.transientCallbackCount, 1);
+  });
+}

packages/flutter_test/lib/src/binding.dart

@@ -226,14 +226,17 @@ abstract class TestWidgetsFlutterBinding extends BindingBase
   /// test failures.
   bool showAppDumpInErrors = false;
 
-  /// Call the callback inside a [FakeAsync] scope on which [pump] can
+  /// Call the testBody inside a [FakeAsync] scope on which [pump] can
   /// advance time.
   ///
   /// Returns a future which completes when the test has run.
   ///
   /// Called by the [testWidgets] and [benchmarkWidgets] functions to
   /// run a test.
-  Future<Null> runTest(Future<Null> callback());
+  ///
+  /// The `invariantTester` argument is called after the `testBody`'s [Future]
+  /// completes. If it throws, then the test is marked as failed.
+  Future<Null> runTest(Future<Null> testBody(), VoidCallback invariantTester);
 
   /// This is called during test execution before and after the body has been
   /// executed.
@@ -266,7 +269,7 @@ abstract class TestWidgetsFlutterBinding extends BindingBase
       _currentTestCompleter.complete(null);
   }
 
-  Future<Null> _runTest(Future<Null> callback()) {
+  Future<Null> _runTest(Future<Null> testBody(), VoidCallback invariantTester) {
     assert(inTest);
     _oldExceptionHandler = FlutterError.onError;
     int _exceptionCount = 0; // number of un-taken exceptions
@@ -357,20 +360,20 @@ abstract class TestWidgetsFlutterBinding extends BindingBase
     );
     _parentZone = Zone.current;
     Zone testZone = _parentZone.fork(specification: errorHandlingZoneSpecification);
-    testZone.runUnaryGuarded(_runTestBody, callback)
+    testZone.runBinaryGuarded(_runTestBody, testBody, invariantTester)
       .whenComplete(_testCompletionHandler);
     asyncBarrier(); // When using AutomatedTestWidgetsFlutterBinding, this flushes the microtasks.
     return _currentTestCompleter.future;
   }
 
-  Future<Null> _runTestBody(Future<Null> callback()) async {
+  Future<Null> _runTestBody(Future<Null> testBody(), VoidCallback invariantTester) async {
     assert(inTest);
 
     runApp(new Container(key: new UniqueKey(), child: _kPreTestMessage)); // Reset the tree to a known state.
     await pump();
 
     // run the test
-    await callback();
+    await testBody();
     asyncBarrier(); // drains the microtasks in `flutter test` mode (when using AutomatedTestWidgetsFlutterBinding)
 
     if (_pendingExceptionDetails == null) {
@@ -379,6 +382,7 @@ abstract class TestWidgetsFlutterBinding extends BindingBase
       // alone so that we don't cause more spurious errors.
       runApp(new Container(key: new UniqueKey(), child: _kPostTestMessage)); // Unmount any remaining widgets.
       await pump();
+      invariantTester();
       _verifyInvariants();
     }
 
@@ -489,24 +493,24 @@ class AutomatedTestWidgetsFlutterBinding extends TestWidgetsFlutterBinding {
   }
 
   @override
-  Future<Null> runTest(Future<Null> callback()) {
+  Future<Null> runTest(Future<Null> testBody(), VoidCallback invariantTester) {
     assert(!inTest);
     assert(_fakeAsync == null);
     assert(_clock == null);
     _fakeAsync = new FakeAsync();
     _clock = _fakeAsync.getClock(new DateTime.utc(2015, 1, 1));
-    Future<Null> callbackResult;
+    Future<Null> testBodyResult;
     _fakeAsync.run((FakeAsync fakeAsync) {
       assert(fakeAsync == _fakeAsync);
-      callbackResult = _runTest(callback);
+      testBodyResult = _runTest(testBody, invariantTester);
       assert(inTest);
     });
-    // callbackResult is a Future that was created in the Zone of the fakeAsync.
+    // testBodyResult is a Future that was created in the Zone of the fakeAsync.
     // This means that if we call .then() on it (as the test framework is about to),
     // it will register a microtask to handle the future _in the fake async zone_.
     // To avoid this, we wrap it in a Future that we've created _outside_ the fake
     // async zone.
-    return new Future<Null>.value(callbackResult);
+    return new Future<Null>.value(testBodyResult);
   }
 
   @override
@@ -686,10 +690,10 @@ class LiveTestWidgetsFlutterBinding extends TestWidgetsFlutterBinding {
   }
 
   @override
-  Future<Null> runTest(Future<Null> callback()) async {
+  Future<Null> runTest(Future<Null> testBody(), VoidCallback invariantTester) async {
     assert(!inTest);
     _inTest = true;
-    return _runTest(callback);
+    return _runTest(testBody, invariantTester);
   }
 
   @override

packages/flutter_test/lib/src/widget_tester.dart

@@ -6,6 +6,7 @@ import 'dart:async';
 
 import 'package:flutter/gestures.dart';
 import 'package:flutter/rendering.dart';
+import 'package:flutter/scheduler.dart';
 import 'package:flutter/widgets.dart';
 import 'package:meta/meta.dart';
 import 'package:test/test.dart' as test_package;
@@ -50,7 +51,7 @@ void testWidgets(String description, WidgetTesterCallback callback, {
   WidgetTester tester = new WidgetTester._(binding);
   timeout ??= binding.defaultTestTimeout;
   test_package.group('-', () {
-    test_package.test(description, () => binding.runTest(() => callback(tester)), skip: skip);
+    test_package.test(description, () => binding.runTest(() => callback(tester), tester._endOfTestVerifications), skip: skip);
     test_package.tearDown(binding.postTest);
   }, timeout: timeout);
 }
@@ -108,7 +109,7 @@ Future<Null> benchmarkWidgets(WidgetTesterCallback callback) {
   TestWidgetsFlutterBinding binding = TestWidgetsFlutterBinding.ensureInitialized();
   assert(binding is! AutomatedTestWidgetsFlutterBinding);
   WidgetTester tester = new WidgetTester._(binding);
-  return binding.runTest(() => callback(tester)) ?? new Future<Null>.value();
+  return binding.runTest(() => callback(tester), tester._endOfTestVerifications) ?? new Future<Null>.value();
 }
 
 /// Assert that `actual` matches `matcher`.
@@ -143,7 +144,10 @@ void expectSync(dynamic actual, dynamic matcher, {
 }
 
 /// Class that programmatically interacts with widgets and the test environment.
-class WidgetTester extends WidgetController implements HitTestDispatcher {
+///
+/// For convenience, instances of this class (such as the one provided by
+/// `testWidget`) can be used as the `vsync` for `AnimationController` objects.
+class WidgetTester extends WidgetController implements HitTestDispatcher, TickerProvider {
   WidgetTester._(TestWidgetsFlutterBinding binding) : super(binding) {
     if (binding is LiveTestWidgetsFlutterBinding)
       binding.deviceEventDispatcher = this;
@@ -328,6 +332,7 @@ class WidgetTester extends WidgetController implements HitTestDispatcher {
   }
 
   bool _isPrivate(Type type) {
+    // used above so that we don't suggest matchers for private types
     return '_'.matchAsPrefix(type.toString()) != null;
   }
 
@@ -348,4 +353,62 @@ class WidgetTester extends WidgetController implements HitTestDispatcher {
   Future<Null> idle() {
     return TestAsyncUtils.guard(() => binding.idle());
   }
+
+  Set<Ticker> _tickers;
+
+  @override
+  Ticker createTicker(TickerCallback onTick) {
+    _tickers ??= new Set<_TestTicker>();
+    final _TestTicker result = new _TestTicker(onTick, _removeTicker);
+    _tickers.add(result);
+    return result;
+  }
+
+  void _removeTicker(_TestTicker ticker) {
+    assert(_tickers != null);
+    assert(_tickers.contains(ticker));
+    _tickers.remove(ticker);
+  }
+
+  /// Throws an exception if any tickers created by the [WidgetTester] are still
+  /// active when the method is called.
+  ///
+  /// An argument can be specified to provide a string that will be used in the
+  /// error message. It should be an adverbial phrase describing the current
+  /// situation, such as "at the end of the test".
+  void verifyTickersWereDisposed([ String when = 'when none should have been' ]) {
+    assert(when != null);
+    if (_tickers != null) {
+      for (Ticker ticker in _tickers) {
+        if (ticker.isActive) {
+          throw new FlutterError(
+            'A Ticker was active $when.\n'
+            'All Tickers must be disposed. Tickers used by AnimationControllers '
+            'should be disposed by calling dispose() on the AnimationController itself. '
+            'Otherwise, the ticker will leak.\n'
+            'The offending ticker was: ${ticker.toString(debugIncludeStack: true)}'
+          );
+        }
+      }
+    }
+  }
+
+  void _endOfTestVerifications() {
+    verifyTickersWereDisposed('at the end of the test');
+  }
+}
+
+typedef void _TickerDisposeCallback(_TestTicker ticker);
+
+class _TestTicker extends Ticker {
+  _TestTicker(TickerCallback onTick, this._onDispose) : super(onTick);
+
+  _TickerDisposeCallback _onDispose;
+
+  @override
+  void dispose() {
+    if (_onDispose != null)
+      _onDispose(this);
+    super.dispose();
+  }
 }

packages/flutter_test/test/widget_tester_test.dart

@@ -73,7 +73,10 @@ void main() {
       await tester.pumpWidget(new Text('foo'));
       int count;
 
-      AnimationController test = new AnimationController(duration: const Duration(milliseconds: 5100));
+      AnimationController test = new AnimationController(
+        duration: const Duration(milliseconds: 5100),
+        vsync: tester,
+      );
       count = await tester.pumpUntilNoTransientCallbacks(const Duration(seconds: 1));
       expect(count, 0);