Update TabBar and TabBar.secondary to use indicator height/color M3 tokens (#145753)

fixes [Secondary `TabBar` indicator height token is missing ](https://github.com/flutter/flutter/issues/124965)

### Code sample

<details>
<summary>expand to view the code sample</summary> 

```dart
import 'package:flutter/material.dart';

void main() => runApp(const MyApp());

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      home: DefaultTabController(
        length: 2,
        child: Scaffold(
          appBar: AppBar(
            title: const Text('Sample'),
            bottom: const TabBar.secondary(
              tabs: <Widget>[
                Tab(icon: Icon(Icons.directions_car)),
                Tab(icon: Icon(Icons.directions_transit)),
              ],
            ),
          ),
          floatingActionButton: FloatingActionButton(
            onPressed: () {},
            child: const Icon(Icons.add),
          ),
        ),
      ),
    );
  }
}
```

</details>

dev/tools/gen_defaults/generated/used_tokens.csv

@@ -599,6 +599,8 @@ md.comp.search-view.header.input-text.color,
 md.comp.search-view.header.input-text.text-style,
 md.comp.search-view.header.supporting-text.color,
 md.comp.search-view.header.supporting-text.text-style,
+md.comp.secondary-navigation-tab.active-indicator.color,
+md.comp.secondary-navigation-tab.active-indicator.height,
 md.comp.secondary-navigation-tab.active.label-text.color,
 md.comp.secondary-navigation-tab.focus.state-layer.color,
 md.comp.secondary-navigation-tab.focus.state-layer.opacity,

dev/tools/gen_defaults/lib/tabs_template.dart

@@ -78,7 +78,12 @@ class _${blockName}PrimaryDefaultsM3 extends TabBarTheme {
   @override
   TabAlignment? get tabAlignment => isScrollable ? TabAlignment.startOffset : TabAlignment.fill;
 
-  static double indicatorWeight = ${getToken('md.comp.primary-navigation-tab.active-indicator.height')};
+  static double indicatorWeight(TabBarIndicatorSize indicatorSize) {
+    return switch (indicatorSize) {
+      TabBarIndicatorSize.label => ${getToken('md.comp.primary-navigation-tab.active-indicator.height')},
+      TabBarIndicatorSize.tab   => ${getToken('md.comp.secondary-navigation-tab.active-indicator.height')},
+    };
+  }
 
   // TODO(davidmartos96): This value doesn't currently exist in
   // https://m3.material.io/components/tabs/specs
@@ -104,7 +109,7 @@ class _${blockName}SecondaryDefaultsM3 extends TabBarTheme {
   double? get dividerHeight => ${getToken("md.comp.divider.thickness")};
 
   @override
-  Color? get indicatorColor => ${componentColor("md.comp.primary-navigation-tab.active-indicator")};
+  Color? get indicatorColor => ${componentColor("md.comp.secondary-navigation-tab.active-indicator")};
 
   @override
   Color? get labelColor => ${componentColor("md.comp.secondary-navigation-tab.active.label-text")};
@@ -151,6 +156,8 @@ class _${blockName}SecondaryDefaultsM3 extends TabBarTheme {
 
   @override
   TabAlignment? get tabAlignment => isScrollable ? TabAlignment.startOffset : TabAlignment.fill;
+
+  static double indicatorWeight = ${getToken('md.comp.secondary-navigation-tab.active-indicator.height')};
 }
 ''';
 

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

@@ -1343,11 +1343,20 @@ class _TabBarState extends State<TabBar> {
       color = Colors.white;
     }
 
-    final bool primaryWithLabelIndicator = widget._isPrimary && indicatorSize == TabBarIndicatorSize.label;
+    final double effectiveIndicatorWeight = theme.useMaterial3
-    final double effectiveIndicatorWeight = theme.useMaterial3 && primaryWithLabelIndicator
+      ? math.max(
-      ? math.max(widget.indicatorWeight, _TabsPrimaryDefaultsM3.indicatorWeight)
+          widget.indicatorWeight,
+          switch (widget._isPrimary) {
+            true  => _TabsPrimaryDefaultsM3.indicatorWeight(indicatorSize),
+            false => _TabsSecondaryDefaultsM3.indicatorWeight,
+          },
+        )
       : widget.indicatorWeight;
     // Only Material 3 primary TabBar with label indicatorSize should be rounded.
+    final bool primaryWithLabelIndicator = switch (indicatorSize) {
+      TabBarIndicatorSize.label  => widget._isPrimary,
+      TabBarIndicatorSize.tab    => false,
+    };
     final BorderRadius? effectiveBorderRadius = theme.useMaterial3 && primaryWithLabelIndicator
       ? BorderRadius.only(
           topLeft: Radius.circular(effectiveIndicatorWeight),
@@ -2429,7 +2438,12 @@ class _TabsPrimaryDefaultsM3 extends TabBarTheme {
   @override
   TabAlignment? get tabAlignment => isScrollable ? TabAlignment.startOffset : TabAlignment.fill;
 
-  static double indicatorWeight = 3.0;
+  static double indicatorWeight(TabBarIndicatorSize indicatorSize) {
+    return switch (indicatorSize) {
+      TabBarIndicatorSize.label => 3.0,
+      TabBarIndicatorSize.tab => 2.0,
+    };
+  }
 
   // TODO(davidmartos96): This value doesn't currently exist in
   // https://m3.material.io/components/tabs/specs
@@ -2502,6 +2516,8 @@ class _TabsSecondaryDefaultsM3 extends TabBarTheme {
 
   @override
   TabAlignment? get tabAlignment => isScrollable ? TabAlignment.startOffset : TabAlignment.fill;
+
+  static double indicatorWeight = 2.0;
 }
 
 // END GENERATED TOKEN PROPERTIES - Tabs

packages/flutter/test/material/tabs_test.dart

@@ -13,9 +13,15 @@ import '../widgets/semantics_tester.dart';
 import 'feedback_tester.dart';
 import 'tabs_utils.dart';
 
-Widget boilerplate({ Widget? child, TextDirection textDirection = TextDirection.ltr, bool? useMaterial3, TabBarTheme? tabBarTheme }) {
+Widget boilerplate({
+  Widget? child,
+  TextDirection textDirection = TextDirection.ltr,
+  ThemeData? theme,
+  TabBarTheme? tabBarTheme,
+  bool? useMaterial3,
+}) {
   return Theme(
-    data: ThemeData(useMaterial3: useMaterial3, tabBarTheme: tabBarTheme),
+    data: theme ?? ThemeData(useMaterial3: useMaterial3, tabBarTheme: tabBarTheme),
     child: Localizations(
       locale: const Locale('en', 'US'),
       delegates: const <LocalizationsDelegate<dynamic>>[
@@ -346,45 +352,48 @@ void main() {
   });
 
   testWidgets('TabBar default tab indicator (primary)', (WidgetTester tester) async {
-    final ThemeData theme = ThemeData(useMaterial3: true);
+    final ThemeData theme = ThemeData();
     final List<Widget> tabs = List<Widget>.generate(4, (int index) {
       return Tab(text: 'Tab $index');
     });
-
     final TabController controller = createTabController(
       vsync: const TestVSync(),
       length: tabs.length,
     );
+    const double indicatorWeightLabel = 3.0;
+    const double indicatorWeightTab = 2.0;
 
-    await tester.pumpWidget(
+    Widget buildTab({ TabBarIndicatorSize? indicatorSize }) {
-      MaterialApp(
+      return MaterialApp(
         home: boilerplate(
-          useMaterial3: theme.useMaterial3,
+          theme: theme,
           child: Container(
             alignment: Alignment.topLeft,
             child: TabBar(
+              indicatorSize: indicatorSize,
               controller: controller,
               tabs: tabs,
             ),
           ),
         ),
-      ),
+      );
-    );
+    }
 
-    final RenderBox tabBarBox = tester.firstRenderObject<RenderBox>(find.byType(TabBar));
+    // Test default tab indicator (TabBarIndicatorSize.label).
+    await tester.pumpWidget(buildTab());
+
+    RenderBox tabBarBox = tester.firstRenderObject<RenderBox>(find.byType(TabBar));
     expect(tabBarBox.size.height, 48.0);
 
-    const double indicatorWeight = 3.0;
+    // Check tab indicator size and color.
-
     final RRect rrect = RRect.fromLTRBAndCorners(
       64.75,
-      tabBarBox.size.height - indicatorWeight,
+      tabBarBox.size.height - indicatorWeightLabel,
       135.25,
       tabBarBox.size.height,
       topLeft: const Radius.circular(3.0),
       topRight: const Radius.circular(3.0),
     );
-
     expect(
       tabBarBox,
       paints
@@ -392,23 +401,52 @@ void main() {
           color: theme.colorScheme.primary,
           rrect: rrect,
     ));
+
+    // Test default tab indicator (TabBarIndicatorSize.tab).
+    await tester.pumpWidget(buildTab(indicatorSize: TabBarIndicatorSize.tab));
+    await tester.pumpAndSettle();
+
+    tabBarBox = tester.firstRenderObject<RenderBox>(find.byType(TabBar));
+    expect(tabBarBox.size.height, 48.0);
+
+    const double indicatorY = 48 - (indicatorWeightTab / 2.0);
+    const double indicatorLeft =  indicatorWeightTab / 2.0;
+    const double indicatorRight = 200.0 - (indicatorWeightTab / 2.0);
+
+    // Check tab indicator size and color.
+    expect(
+      tabBarBox,
+      paints
+        // Divider.
+        ..line(
+          color: theme.colorScheme.outlineVariant,
+        )
+        // Tab indicator.
+        ..line(
+          color: theme.colorScheme.primary,
+          strokeWidth: indicatorWeightTab,
+          p1: const Offset(indicatorLeft, indicatorY),
+          p2: const Offset(indicatorRight, indicatorY),
+        ),
+    );
   });
 
   testWidgets('TabBar default tab indicator (secondary)', (WidgetTester tester) async {
-    final ThemeData theme = ThemeData(useMaterial3: true);
+    final ThemeData theme = ThemeData();
     final List<Widget> tabs = List<Widget>.generate(4, (int index) {
       return Tab(text: 'Tab $index');
     });
-
     final TabController controller = createTabController(
       vsync: const TestVSync(),
       length: tabs.length,
     );
+    const double indicatorWeight = 2.0;
 
+    // Test default tab indicator.
     await tester.pumpWidget(
       MaterialApp(
         home: boilerplate(
-          useMaterial3: theme.useMaterial3,
+          theme: theme,
           child: Container(
             alignment: Alignment.topLeft,
             child: TabBar.secondary(
@@ -423,26 +461,26 @@ void main() {
     final RenderBox tabBarBox = tester.firstRenderObject<RenderBox>(find.byType(TabBar));
     expect(tabBarBox.size.height, 48.0);
 
-    const double indicatorWeight = 2.0;
     const double indicatorY = 48 - (indicatorWeight / 2.0);
     const double indicatorLeft =  indicatorWeight / 2.0;
     const double indicatorRight = 200.0 - (indicatorWeight / 2.0);
 
+    // Check tab indicator size and color.
     expect(
       tabBarBox,
       paints
-        // Divider
+        // Divider.
         ..line(
           color: theme.colorScheme.outlineVariant,
         )
-        // Tab indicator
+        // Tab indicator.
         ..line(
           color: theme.colorScheme.primary,
           strokeWidth: indicatorWeight,
           p1: const Offset(indicatorLeft, indicatorY),
           p2: const Offset(indicatorRight, indicatorY),
         ),
-      );
+    );
   });
 
   testWidgets('TabBar default overlay (primary)', (WidgetTester tester) async {