Add tooltip for the clear button on SearchAnchor's search view (#141804)

Fixes #141347
This PR is to add a "clear text" tooltip for the clear button on `SearchAnchor`'s search view and also add a `clearButtonTooltip` entry for `material_localizations`.

Author: QuncCccccc

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

@@ -32,6 +32,9 @@ abstract class MaterialLocalizations {
   /// The [BackButton]'s tooltip.
   String get backButtonTooltip;
 
+  /// The tooltip for the clear button to clear text on [SearchAnchor]'s search view.
+  String get clearButtonTooltip;
+
   /// The [CloseButton]'s tooltip.
   String get closeButtonTooltip;
 
@@ -1053,6 +1056,9 @@ class DefaultMaterialLocalizations implements MaterialLocalizations {
   @override
   String get backButtonTooltip => 'Back';
 
+  @override
+  String get clearButtonTooltip => 'Clear text';
+
   @override
   String get closeButtonTooltip => 'Close';
 

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

@@ -20,6 +20,7 @@ import 'ink_well.dart';
 import 'input_border.dart';
 import 'input_decorator.dart';
 import 'material.dart';
+import 'material_localizations.dart';
 import 'material_state.dart';
 import 'search_bar_theme.dart';
 import 'search_view_theme.dart';
@@ -811,13 +812,15 @@ class _ViewContentState extends State<_ViewContent> {
   Widget build(BuildContext context) {
     final Widget defaultLeading = IconButton(
       icon: const Icon(Icons.arrow_back),
+      tooltip: MaterialLocalizations.of(context).backButtonTooltip,
       onPressed: () { Navigator.of(context).pop(); },
       style: const ButtonStyle(tapTargetSize: MaterialTapTargetSize.shrinkWrap),
     );
 
     final List<Widget> defaultTrailing = <Widget>[
       if (_controller.text.isNotEmpty) IconButton(
         icon: const Icon(Icons.close),
+        tooltip: MaterialLocalizations.of(context).clearButtonTooltip,
         onPressed: () {
           _controller.clear();
         },

packages/flutter/test/material/localizations_test.dart

@@ -11,6 +11,7 @@ void main() {
 
     expect(localizations.openAppDrawerTooltip, isNotNull);
     expect(localizations.backButtonTooltip, isNotNull);
+    expect(localizations.clearButtonTooltip, isNotNull);
     expect(localizations.closeButtonTooltip, isNotNull);
     expect(localizations.deleteButtonTooltip, isNotNull);
     expect(localizations.moreButtonTooltip, isNotNull);