Pass-through maxLines in DropdownMenu (#161903)

Pass-through `maxLines` in `DropdownMenu`.

Fixes #161881 

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- [x] I listed at least one issue that this PR fixes in the description
above.
- [x] I updated/added relevant documentation (doc comments with `///`).
- [x] I added new tests to check the change I am making, or this PR is
[test-exempt].
- [x] I followed the [breaking change policy] and added [Data Driven
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---------

Co-authored-by: Taha Tesser <tessertaha@gmail.com>

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

@@ -188,6 +188,7 @@ class DropdownMenu<T> extends StatefulWidget {
     required this.dropdownMenuEntries,
     this.inputFormatters,
     this.closeBehavior = DropdownMenuCloseBehavior.all,
+    this.maxLines = 1,
   }) : assert(filterCallback == null || enableFilter);
 
   /// Determine if the [DropdownMenu] is enabled.
@@ -502,6 +503,26 @@ class DropdownMenu<T> extends StatefulWidget {
   /// Defaults to [DropdownMenuCloseBehavior.all].
   final DropdownMenuCloseBehavior closeBehavior;
 
+  /// Specifies the maximum number of lines the selected value can display
+  /// in the [DropdownMenu].
+  ///
+  /// If the provided value is 1, then the text will not wrap, but will scroll
+  /// horizontally instead. Defaults to 1.
+  ///
+  /// If this is null, there is no limit to the number of lines, and the text
+  /// container will start with enough vertical space for one line and
+  /// automatically grow to accommodate additional lines as they are entered, up
+  /// to the height of its constraints.
+  ///
+  /// If this is not null, the provided value must be greater than zero. The text
+  /// field will restrict the input to the given number of lines and take up enough
+  /// horizontal space to accommodate that number of lines.
+  ///
+  /// See also:
+  ///  * [TextField.maxLines], which specifies the maximum number of lines
+  ///    the [TextField] can display.
+  final int? maxLines;
+
   @override
   State<DropdownMenu<T>> createState() => _DropdownMenuState<T>();
 }
@@ -1005,6 +1026,7 @@ class _DropdownMenuState<T> extends State<DropdownMenu<T>> {
           keyboardType: widget.keyboardType,
           textAlign: widget.textAlign,
           textAlignVertical: TextAlignVertical.center,
+          maxLines: widget.maxLines,
           style: effectiveTextStyle,
           controller: _localTextEditingController,
           onEditingComplete: _handleEditingComplete,

packages/flutter/test/material/dropdown_menu_test.dart

@@ -3901,6 +3901,35 @@ void main() {
     },
     variant: TargetPlatformVariant.all(),
   );
+
+  testWidgets('DropdownMenu passes maxLines to TextField', (WidgetTester tester) async {
+    await tester.pumpWidget(
+      MaterialApp(home: Scaffold(body: DropdownMenu<TestMenu>(dropdownMenuEntries: menuChildren))),
+    );
+    TextField textField = tester.widget(find.byType(TextField));
+    // Default behavior.
+    expect(textField.maxLines, 1);
+
+    await tester.pumpWidget(
+      MaterialApp(
+        home: Scaffold(
+          body: DropdownMenu<TestMenu>(dropdownMenuEntries: menuChildren, maxLines: null),
+        ),
+      ),
+    );
+    textField = tester.widget(find.byType(TextField));
+    expect(textField.maxLines, null);
+
+    await tester.pumpWidget(
+      MaterialApp(
+        home: Scaffold(
+          body: DropdownMenu<TestMenu>(dropdownMenuEntries: menuChildren, maxLines: 2),
+        ),
+      ),
+    );
+    textField = tester.widget(find.byType(TextField));
+    expect(textField.maxLines, 2);
+  });
 }
 
 enum TestMenu {