Update SystemUIOverlayStyle to support null contrast enforcement (#91396)

packages/flutter/lib/src/rendering/view.dart

@@ -300,9 +300,11 @@ class RenderView extends RenderObject with RenderObjectWithChildMixin<RenderBox>
         statusBarBrightness: upperOverlayStyle?.statusBarBrightness,
         statusBarIconBrightness: upperOverlayStyle?.statusBarIconBrightness,
         statusBarColor: upperOverlayStyle?.statusBarColor,
+        systemStatusBarContrastEnforced: upperOverlayStyle?.systemStatusBarContrastEnforced,
         systemNavigationBarColor: lowerOverlayStyle?.systemNavigationBarColor,
         systemNavigationBarDividerColor: lowerOverlayStyle?.systemNavigationBarDividerColor,
         systemNavigationBarIconBrightness: lowerOverlayStyle?.systemNavigationBarIconBrightness,
+        systemNavigationBarContrastEnforced: lowerOverlayStyle?.systemNavigationBarContrastEnforced,
       );
       SystemChrome.setSystemUIOverlayStyle(overlayStyle);
     }

packages/flutter/lib/src/services/system_chrome.dart

@@ -289,12 +289,12 @@ class SystemUiOverlayStyle {
     return <String, dynamic>{
       'systemNavigationBarColor': systemNavigationBarColor?.value,
       'systemNavigationBarDividerColor': systemNavigationBarDividerColor?.value,
-      'systemStatusBarContrastEnforced' : systemStatusBarContrastEnforced ?? true,
+      'systemStatusBarContrastEnforced': systemStatusBarContrastEnforced,
       'statusBarColor': statusBarColor?.value,
       'statusBarBrightness': statusBarBrightness?.toString(),
       'statusBarIconBrightness': statusBarIconBrightness?.toString(),
       'systemNavigationBarIconBrightness': systemNavigationBarIconBrightness?.toString(),
-      'systemNavigationBarContrastEnforced' : systemNavigationBarContrastEnforced ?? true,
+      'systemNavigationBarContrastEnforced': systemNavigationBarContrastEnforced,
     };
   }
 

packages/flutter/test/services/system_chrome_test.dart

@@ -10,17 +10,60 @@ void main() {
   TestWidgetsFlutterBinding.ensureInitialized();
 
   testWidgets('SystemChrome overlay style test', (WidgetTester tester) async {
+    final List<MethodCall> log = <MethodCall>[];
+
+    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, (MethodCall methodCall) async {
+      log.add(methodCall);
+    });
+
     // The first call is a cache miss and will queue a microtask
     SystemChrome.setSystemUIOverlayStyle(SystemUiOverlayStyle.light);
     expect(tester.binding.microtaskCount, equals(1));
 
     // Flush all microtasks
     await tester.idle();
+    expect(log, hasLength(1));
+    expect(log.single, isMethodCall(
+      'SystemChrome.setSystemUIOverlayStyle',
+      arguments: <String, dynamic>{
+        'systemNavigationBarColor': 4278190080,
+        'systemNavigationBarDividerColor': null,
+        'systemStatusBarContrastEnforced': null,
+        'statusBarColor': null,
+        'statusBarBrightness': 'Brightness.dark',
+        'statusBarIconBrightness': 'Brightness.light',
+        'systemNavigationBarIconBrightness': 'Brightness.light',
+        'systemNavigationBarContrastEnforced': null
+      },
+    ));
+    log.clear();
     expect(tester.binding.microtaskCount, equals(0));
+    expect(log.isEmpty, isTrue);
 
     // The second call with the same value should be a no-op
     SystemChrome.setSystemUIOverlayStyle(SystemUiOverlayStyle.light);
     expect(tester.binding.microtaskCount, equals(0));
+
+    SystemChrome.setSystemUIOverlayStyle(const SystemUiOverlayStyle(
+      systemStatusBarContrastEnforced: false,
+      systemNavigationBarContrastEnforced: true
+    ));
+    expect(tester.binding.microtaskCount, equals(1));
+    await tester.idle();
+    expect(log, hasLength(1));
+    expect(log.single, isMethodCall(
+      'SystemChrome.setSystemUIOverlayStyle',
+      arguments: <String, dynamic>{
+        'systemNavigationBarColor': null,
+        'systemNavigationBarDividerColor': null,
+        'systemStatusBarContrastEnforced': false,
+        'statusBarColor': null,
+        'statusBarBrightness': null,
+        'statusBarIconBrightness': null,
+        'systemNavigationBarIconBrightness': null,
+        'systemNavigationBarContrastEnforced': true
+      },
+    ));
   });
 
   test('setPreferredOrientations control test', () async {
@@ -157,12 +200,12 @@ void main() {
     expect(systemUiOverlayStyle.toString(), 'SystemUiOverlayStyle({'
       'systemNavigationBarColor: null, '
       'systemNavigationBarDividerColor: null, '
-      'systemStatusBarContrastEnforced: true, '
+      'systemStatusBarContrastEnforced: null, '
       'statusBarColor: null, '
       'statusBarBrightness: null, '
       'statusBarIconBrightness: null, '
       'systemNavigationBarIconBrightness: null, '
-      'systemNavigationBarContrastEnforced: true})',
+      'systemNavigationBarContrastEnforced: null})',
     );
   });
 }