setState() will call scheduleFrame() in post-frame callback now. (#56968)

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

@@ -83,11 +83,7 @@ class _SemanticsDebuggerState extends State<SemanticsDebugger> with WidgetsBindi
     SchedulerBinding.instance.addPostFrameCallback((Duration timeStamp) {
       // Semantic information are only available at the end of a frame and our
       // only chance to paint them on the screen is the next frame. To achieve
-      // this, we call setState() in a post-frame callback. THIS PATTERN SHOULD
-      // NOT BE COPIED. Calling setState() in a post-frame callback is a bad
-      // idea as it will not schedule a frame and your app may be lagging behind
-      // by one frame. We manually call scheduleFrame() to force a frame and
-      // ensure that the semantic information are always painted on the screen.
+      // this, we call setState() in a post-frame callback.
       if (mounted) {
         // If we got disposed this frame, we will still get an update,
         // because the inactive list is flushed after the semantics updates
@@ -95,7 +91,6 @@ class _SemanticsDebuggerState extends State<SemanticsDebugger> with WidgetsBindi
         setState(() {
           // The generation of the _SemanticsDebuggerListener has changed.
         });
-        SchedulerBinding.instance.scheduleFrame();
       }
     });
   }

packages/flutter/test/widgets/semantics_debugger_test.dart

@@ -10,6 +10,16 @@ import 'package:flutter/rendering.dart';
 import 'package:flutter_test/flutter_test.dart';
 
 void main() {
+  testWidgets('SemanticsDebugger will schedule a frame', (WidgetTester tester) async {
+    await tester.pumpWidget(
+      SemanticsDebugger(
+        child: Container(),
+      ),
+    );
+
+    expect(tester.binding.hasScheduledFrame, isTrue);
+  });
+
   testWidgets('SemanticsDebugger smoke test', (WidgetTester tester) async {
 
     // This is a smoketest to verify that adding a debugger doesn't crash.