Removed ButtonBar from the Scaffold and About widgets (#76246)

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

@@ -11,7 +11,6 @@ import 'package:flutter/widgets.dart' hide Flow;
 
 import 'app_bar.dart';
 import 'back_button.dart';
-import 'button_bar.dart';
 import 'card.dart';
 import 'constants.dart';
 import 'debug.dart';
@@ -1534,13 +1533,17 @@ class _MasterDetailScaffoldState extends State<_MasterDetailScaffold>
                 mainAxisAlignment: MainAxisAlignment.start,
                 children: <Widget>[
                   ConstrainedBox(
-                    constraints:
-                    BoxConstraints.tightFor(width: masterViewWidth),
+                    constraints: BoxConstraints.tightFor(width: masterViewWidth),
                     child: IconTheme(
                       data: Theme.of(context).primaryIconTheme,
-                      child: ButtonBar(
-                        children:
-                        widget.actionBuilder!(context, _ActionLevel.view),
+                      child: Container(
+                        alignment: AlignmentDirectional.centerEnd,
+                        padding: const EdgeInsets.all(8),
+                        child: OverflowBar(
+                          spacing: 8,
+                          overflowAlignment: OverflowBarAlignment.end,
+                          children: widget.actionBuilder!(context, _ActionLevel.view),
+                        ),
                       ),
                     ),
                   )

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

@@ -13,7 +13,6 @@ import 'package:flutter/gestures.dart' show DragStartBehavior;
 
 import 'app_bar.dart';
 import 'bottom_sheet.dart';
-import 'button_bar.dart';
 import 'colors.dart';
 import 'curves.dart';
 import 'debug.dart';
@@ -1555,7 +1554,7 @@ class Scaffold extends StatefulWidget {
   /// Typically this is a list of [TextButton] widgets. These buttons are
   /// persistently visible, even if the [body] of the scaffold scrolls.
   ///
-  /// These widgets will be wrapped in a [ButtonBar].
+  /// These widgets will be wrapped in an [OverflowBar].
   ///
   /// The [persistentFooterButtons] are rendered above the
   /// [bottomNavigationBar] but below the [body].
@@ -3114,11 +3113,19 @@ class ScaffoldState extends State<Scaffold> with TickerProviderStateMixin, Resto
           ),
           child: SafeArea(
             top: false,
-            child: ButtonBar(
+            child: IntrinsicHeight(
+              child: Container(
+                alignment: AlignmentDirectional.centerEnd,
+                padding: const EdgeInsets.all(8),
+                child: OverflowBar(
+                  spacing: 8,
+                  overflowAlignment: OverflowBarAlignment.end,
                   children: widget.persistentFooterButtons!,
                 ),
               ),
             ),
+          ),
+        ),
         _ScaffoldSlot.persistentFooter,
         removeLeftPadding: false,
         removeTopPadding: true,

packages/flutter/test/material/scaffold_test.dart

@@ -492,8 +492,8 @@ void main() {
         ),
       ),
     );
-    expect(tester.getBottomLeft(find.byType(ButtonBar)), const Offset(10.0, 560.0));
-    expect(tester.getBottomRight(find.byType(ButtonBar)), const Offset(770.0, 560.0));
+    expect(tester.getBottomLeft(_findButtonBar()), const Offset(10.0, 560.0));
+    expect(tester.getBottomRight(_findButtonBar()), const Offset(770.0, 560.0));
   });
 
   testWidgets('Persistent bottom buttons bottom padding is not consumed by viewInsets', (WidgetTester tester) async {
@@ -2293,3 +2293,10 @@ class _CustomPageRoute<T> extends PageRoute<T> {
     return child;
   }
 }
+
+// What was the Scaffold's ButtonBar when many of these tests were written,
+// is now a Container with an OverflowBar child. The Container's size and location
+// match the original ButtonBar's size and location.
+Finder _findButtonBar() {
+  return find.ancestor(of: find.byType(OverflowBar), matching: find.byType(Container)).first;
+}