Add WidgetsApp.debugShowWidgetInspectorOverride again (deprecated) (#145334)

`WidgetsApp.debugShowWidgetInspectorOverride` was replaced with ` WidgetsBinding.instance.debugShowWidgetInspectorOverrideNotifier` in https://github.com/flutter/flutter/pull/144029.

The old API was removed, not deprecated.

It is used by some [open-source projects](https://github.com/search?q=WidgetsApp.debugShowWidgetInspectorOverride&type=code), thus I'm making the effort of bringing the API back as deprecated.

Fixes https://github.com/flutter/flutter/issues/145333

packages/flutter/lib/src/widgets/app.dart

@@ -1193,6 +1193,36 @@ class WidgetsApp extends StatefulWidget {
   /// Used by the `showPerformanceOverlay` VM service extension.
   static bool showPerformanceOverlayOverride = false;
 
+  /// If true, forces the widget inspector to be visible.
+  ///
+  /// Deprecated.
+  /// Use WidgetsBinding.instance.debugShowWidgetInspectorOverrideNotifier.value
+  /// instead.
+  ///
+  /// Overrides the `debugShowWidgetInspector` value set in [WidgetsApp].
+  ///
+  /// Used by the `debugShowWidgetInspector` debugging extension.
+  ///
+  /// The inspector allows the selection of a location on your device or emulator
+  /// and view what widgets and render objects associated with it. An outline of
+  /// the selected widget and some summary information is shown on device and
+  /// more detailed information is shown in the IDE or DevTools.
+  @Deprecated(
+    'Use WidgetsBinding.instance.debugShowWidgetInspectorOverrideNotifier.value instead. '
+    'This feature was deprecated after v3.20.0-14.0.pre.',
+  )
+  static bool get debugShowWidgetInspectorOverride {
+    return WidgetsBinding.instance.debugShowWidgetInspectorOverrideNotifier.value;
+  }
+
+  @Deprecated(
+    'Use WidgetsBinding.instance.debugShowWidgetInspectorOverrideNotifier.value instead. '
+    'This feature was deprecated after v3.20.0-14.0.pre.',
+  )
+  static set debugShowWidgetInspectorOverride(bool value) {
+    WidgetsBinding.instance.debugShowWidgetInspectorOverrideNotifier.value = value;
+  }
+
   /// If false, prevents the debug banner from being visible.
   ///
   /// Used by the `debugAllowBanner` VM service extension.

packages/flutter/test/widgets/widget_inspector_test.dart

@@ -4198,6 +4198,97 @@ class _TestWidgetInspectorService extends TestWidgetInspectorService {
       expect(WidgetsBinding.instance.debugShowWidgetInspectorOverride, isFalse);
     });
 
+    testWidgets('ext.flutter.inspector.show via WidgetsApp.debugShowWidgetInspectorOverride', (WidgetTester tester) async {
+      final Iterable<Map<Object, Object?>> extensionChangedEvents = service.getServiceExtensionStateChangedEvents('ext.flutter.inspector.show');
+      Map<Object, Object?> extensionChangedEvent;
+      int debugShowChangeCounter = 0;
+
+      final GlobalKey key = GlobalKey();
+      await tester.pumpWidget(
+        WidgetsApp(
+          key: key,
+          builder: (BuildContext context, Widget? child) {
+            return const Placeholder();
+          },
+          color: const Color(0xFF123456),
+        ),
+      );
+
+      final ValueListenableBuilder<bool> valueListenableBuilderWidget = tester.widget(
+        find.byType(ValueListenableBuilder<bool>),
+      );
+      void debugShowWidgetInspectorOverrideCallback() {
+        debugShowChangeCounter++;
+      }
+
+      WidgetsApp.debugShowWidgetInspectorOverride = false;
+      valueListenableBuilderWidget.valueListenable.addListener(debugShowWidgetInspectorOverrideCallback);
+
+      service.rebuildCount = 0;
+      expect(extensionChangedEvents, isEmpty);
+      expect(
+        await service.testBoolExtension(
+          WidgetInspectorServiceExtensions.show.name,
+          <String, String>{'enabled': 'true'},
+        ),
+        equals('true'),
+      );
+      expect(extensionChangedEvents.length, equals(1));
+      extensionChangedEvent = extensionChangedEvents.last;
+      expect(extensionChangedEvent['extension'], equals('ext.flutter.inspector.show'));
+      expect(extensionChangedEvent['value'], isTrue);
+      expect(service.rebuildCount, equals(0)); // Should not be force rebuilt.
+      expect(debugShowChangeCounter, equals(1));
+      expect(
+        await service.testBoolExtension(
+          WidgetInspectorServiceExtensions.show.name,
+          <String, String>{},
+        ),
+        equals('true'),
+      );
+      expect(WidgetsApp.debugShowWidgetInspectorOverride, isTrue);
+      expect(extensionChangedEvents.length, equals(1));
+      expect(service.rebuildCount, equals(0)); // Should not be force rebuilt.
+      expect(debugShowChangeCounter, equals(1));
+      expect(
+        await service.testBoolExtension(
+          WidgetInspectorServiceExtensions.show.name,
+          <String, String>{'enabled': 'true'},
+        ),
+        equals('true'),
+      );
+      expect(extensionChangedEvents.length, equals(2));
+      extensionChangedEvent = extensionChangedEvents.last;
+      expect(extensionChangedEvent['extension'], equals('ext.flutter.inspector.show'));
+      expect(extensionChangedEvent['value'], isTrue);
+      expect(service.rebuildCount, equals(0)); // Should not be force rebuilt.
+      expect(debugShowChangeCounter, equals(1));
+      expect(
+        await service.testBoolExtension(
+          WidgetInspectorServiceExtensions.show.name,
+          <String, String>{'enabled': 'false'},
+        ),
+        equals('false'),
+      );
+      expect(extensionChangedEvents.length, equals(3));
+      extensionChangedEvent = extensionChangedEvents.last;
+      expect(extensionChangedEvent['extension'], equals('ext.flutter.inspector.show'));
+      expect(extensionChangedEvent['value'], isFalse);
+      expect(service.rebuildCount, equals(0)); // Should not be force rebuilt.
+      expect(debugShowChangeCounter, equals(2));
+      expect(
+        await service.testBoolExtension(
+          WidgetInspectorServiceExtensions.show.name,
+          <String, String>{},
+        ),
+        equals('false'),
+      );
+      expect(extensionChangedEvents.length, equals(3));
+      expect(service.rebuildCount, equals(0)); // Should not be force rebuilt.
+      expect(debugShowChangeCounter, equals(2));
+      expect(WidgetsApp.debugShowWidgetInspectorOverride, isFalse);
+    });
+
     testWidgets('ext.flutter.inspector.screenshot', (WidgetTester tester) async {
       final GlobalKey outerContainerKey = GlobalKey();
       final GlobalKey paddingKey = GlobalKey();