Replace uses of ButtonBar in doc/samples with Overflowbar (#85358)

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

@@ -1355,52 +1355,58 @@ class _SliverAppBarDelegate extends SliverPersistentHeaderDelegate {
 ///       ],
 ///     ),
 ///     bottomNavigationBar: BottomAppBar(
-///       child: ButtonBar(
-///         alignment: MainAxisAlignment.spaceEvenly,
-///         children: <Widget>[
-///           Row(
-///             children: <Widget>[
-///               const Text('pinned'),
-///               Switch(
-///                 onChanged: (bool val) {
-///                   setState(() {
-///                     _pinned = val;
-///                   });
-///                 },
-///                 value: _pinned,
-///               ),
-///             ],
-///           ),
-///           Row(
-///             children: <Widget>[
-///               const Text('snap'),
-///               Switch(
-///                 onChanged: (bool val) {
-///                   setState(() {
-///                     _snap = val;
-///                     // Snapping only applies when the app bar is floating.
-///                     _floating = _floating || _snap;
-///                   });
-///                 },
-///                 value: _snap,
-///               ),
-///             ],
-///           ),
-///           Row(
-///             children: <Widget>[
-///               const Text('floating'),
-///               Switch(
-///                 onChanged: (bool val) {
-///                   setState(() {
-///                     _floating = val;
-///                     _snap = _snap && _floating;
-///                   });
-///                 },
-///                 value: _floating,
-///               ),
-///             ],
-///           ),
-///         ],
+///       child: Padding(
+///         padding: const EdgeInsets.all(8),
+///         child: OverflowBar(
+///           alignment: MainAxisAlignment.spaceEvenly,
+///           children: <Widget>[
+///             Row(
+///               mainAxisSize: MainAxisSize.min,
+///               children: <Widget>[
+///                 const Text('pinned'),
+///                 Switch(
+///                   onChanged: (bool val) {
+///                     setState(() {
+///                       _pinned = val;
+///                     });
+///                   },
+///                   value: _pinned,
+///                 ),
+///               ],
+///             ),
+///             Row(
+///               mainAxisSize: MainAxisSize.min,
+///               children: <Widget>[
+///                 const Text('snap'),
+///                 Switch(
+///                   onChanged: (bool val) {
+///                     setState(() {
+///                       _snap = val;
+///                       // Snapping only applies when the app bar is floating.
+///                       _floating = _floating || _snap;
+///                     });
+///                   },
+///                   value: _snap,
+///                 ),
+///               ],
+///             ),
+///             Row(
+///               mainAxisSize: MainAxisSize.min,
+///               children: <Widget>[
+///                 const Text('floating'),
+///                 Switch(
+///                   onChanged: (bool val) {
+///                     setState(() {
+///                       _floating = val;
+///                       _snap = _snap && _floating;
+///                     });
+///                   },
+///                   value: _floating,
+///                 ),
+///               ],
+///             ),
+///           ],
+///         ),
 ///       ),
 ///     ),
 ///   );

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

@@ -6,7 +6,6 @@ import 'dart:ui';
 
 import 'package:flutter/widgets.dart';
 
-import 'button_bar.dart';
 import 'colors.dart';
 import 'debug.dart';
 import 'dialog_theme.dart';
@@ -339,18 +338,15 @@ class AlertDialog extends StatelessWidget {
   final TextStyle? contentTextStyle;
 
   /// The (optional) set of actions that are displayed at the bottom of the
-  /// dialog.
+  /// dialog with an [OverflowBar].
   ///
   /// Typically this is a list of [TextButton] widgets. It is recommended to
   /// set the [Text.textAlign] to [TextAlign.end] for the [Text] within the
   /// [TextButton], so that buttons whose labels wrap to an extra line align
-  /// with the overall [ButtonBar]'s alignment within the dialog.
-  ///
-  /// These widgets will be wrapped in a [ButtonBar], which introduces 8 pixels
-  /// of padding on each side.
+  /// with the overall [OverflowBar]'s alignment within the dialog.
   ///
   /// If the [title] is not null but the [content] _is_ null, then an extra 20
-  /// pixels of padding is added above the [ButtonBar] to separate the [title]
+  /// pixels of padding is added above the [OverflowBar] to separate the [title]
   /// from the [actions].
   final List<Widget>? actions;
 
@@ -381,7 +377,7 @@ class AlertDialog extends StatelessWidget {
   ///
   /// See also:
   ///
-  /// * [ButtonBar], which [actions] configures to lay itself out.
+  /// * [OverflowBar], which [actions] configures to lay itself out.
   final EdgeInsetsGeometry actionsPadding;
 
   /// Defines the horizontal layout of the [actions] according to the same
@@ -404,16 +400,13 @@ class AlertDialog extends StatelessWidget {
   /// property is set to [VerticalDirection.up], since it "starts" at the
   /// bottom and "ends" at the top.
   ///
-  /// If null then it will use the surrounding
-  /// [ButtonBarThemeData.overflowDirection]. If that is null, it will
-  /// default to [VerticalDirection.down].
-  ///
   /// See also:
   ///
-  /// * [ButtonBar], which [actions] configures to lay itself out.
+  /// * [OverflowBar], which [actions] configures to lay itself out.
   final VerticalDirection? actionsOverflowDirection;
 
-  /// The spacing between [actions] when the button bar overflows.
+  /// The spacing between [actions] when the [OverflowBar] switches
+  /// to a column layout because the actions don't fit horizontally.
   ///
   /// If the widgets in [actions] do not fit into a single row, they are
   /// arranged into a column. This parameter provides additional