Migrate Scaffold SnackBars in the framework to ScaffoldMessenger (#67946)

dev/benchmarks/test_apps/stocks/lib/stock_home.dart

@@ -247,7 +247,7 @@ class StockHomeState extends State<StockHome> {
       stock.percentChange = 100.0 * (1.0 / stock.lastSale);
       stock.lastSale += 1.0;
     });
-    _scaffoldKey.currentState.showSnackBar(SnackBar(
+    ScaffoldMessenger.of(context).showSnackBar(SnackBar(
       content: Text('Purchased ${stock.symbol} for ${stock.lastSale}'),
       action: SnackBarAction(
         label: 'BUY MORE',

dev/integration_tests/android_views/lib/motion_events_page.dart

@@ -187,7 +187,7 @@ class MotionEventsBodyState extends State<MotionEventsBody> {
   }
 
   void showMessage(BuildContext context, String message) {
-    Scaffold.of(context).showSnackBar(SnackBar(
+    ScaffoldMessenger.of(context).showSnackBar(SnackBar(
       content: Text(message),
       duration: const Duration(seconds: 3),
     ));

dev/integration_tests/flutter_gallery/lib/demo/contacts_demo.dart

@@ -95,7 +95,6 @@ class ContactsDemo extends StatefulWidget {
 enum AppBarBehavior { normal, pinned, floating, snapping }
 
 class ContactsDemoState extends State<ContactsDemo> {
-  static final GlobalKey<ScaffoldState> _scaffoldKey = GlobalKey<ScaffoldState>();
   final double _appBarHeight = 256.0;
 
   AppBarBehavior _appBarBehavior = AppBarBehavior.pinned;
@@ -109,7 +108,6 @@ class ContactsDemoState extends State<ContactsDemo> {
         platform: Theme.of(context).platform,
       ),
       child: Scaffold(
-        key: _scaffoldKey,
         body: CustomScrollView(
           slivers: <Widget>[
             SliverAppBar(
@@ -122,7 +120,7 @@ class ContactsDemoState extends State<ContactsDemo> {
                   icon: const Icon(Icons.create),
                   tooltip: 'Edit',
                   onPressed: () {
-                    _scaffoldKey.currentState.showSnackBar(const SnackBar(
+                    ScaffoldMessenger.of(context).showSnackBar(const SnackBar(
                       content: Text("Editing isn't supported in this screen."),
                     ));
                   },
@@ -190,7 +188,7 @@ class ContactsDemoState extends State<ContactsDemo> {
                         icon: Icons.message,
                         tooltip: 'Send message',
                         onPressed: () {
-                          _scaffoldKey.currentState.showSnackBar(const SnackBar(
+                          ScaffoldMessenger.of(context).showSnackBar(const SnackBar(
                             content: Text('Pretend that this opened your SMS application.'),
                           ));
                         },
@@ -203,7 +201,7 @@ class ContactsDemoState extends State<ContactsDemo> {
                         icon: Icons.message,
                         tooltip: 'Send message',
                         onPressed: () {
-                          _scaffoldKey.currentState.showSnackBar(const SnackBar(
+                          ScaffoldMessenger.of(context).showSnackBar(const SnackBar(
                             content: Text('A messaging app appears.'),
                           ));
                         },
@@ -216,7 +214,7 @@ class ContactsDemoState extends State<ContactsDemo> {
                         icon: Icons.message,
                         tooltip: 'Send message',
                         onPressed: () {
-                          _scaffoldKey.currentState.showSnackBar(const SnackBar(
+                          ScaffoldMessenger.of(context).showSnackBar(const SnackBar(
                             content: Text('Imagine if you will, a messaging application.'),
                           ));
                         },
@@ -235,7 +233,7 @@ class ContactsDemoState extends State<ContactsDemo> {
                       icon: Icons.email,
                       tooltip: 'Send personal e-mail',
                       onPressed: () {
-                        _scaffoldKey.currentState.showSnackBar(const SnackBar(
+                        ScaffoldMessenger.of(context).showSnackBar(const SnackBar(
                           content: Text('Here, your e-mail application would open.'),
                         ));
                       },
@@ -248,7 +246,7 @@ class ContactsDemoState extends State<ContactsDemo> {
                       icon: Icons.email,
                       tooltip: 'Send work e-mail',
                       onPressed: () {
-                        _scaffoldKey.currentState.showSnackBar(const SnackBar(
+                        ScaffoldMessenger.of(context).showSnackBar(const SnackBar(
                           content: Text('Summon your favorite e-mail application here.'),
                         ));
                       },
@@ -266,7 +264,7 @@ class ContactsDemoState extends State<ContactsDemo> {
                       icon: Icons.map,
                       tooltip: 'Open map',
                       onPressed: () {
-                        _scaffoldKey.currentState.showSnackBar(const SnackBar(
+                        ScaffoldMessenger.of(context).showSnackBar(const SnackBar(
                           content: Text('This would show a map of San Francisco.'),
                         ));
                       },
@@ -280,7 +278,7 @@ class ContactsDemoState extends State<ContactsDemo> {
                       icon: Icons.map,
                       tooltip: 'Open map',
                       onPressed: () {
-                        _scaffoldKey.currentState.showSnackBar(const SnackBar(
+                        ScaffoldMessenger.of(context).showSnackBar(const SnackBar(
                           content: Text('This would show a map of Mountain View.'),
                         ));
                       },
@@ -294,7 +292,7 @@ class ContactsDemoState extends State<ContactsDemo> {
                       icon: Icons.map,
                       tooltip: 'Open map',
                       onPressed: () {
-                        _scaffoldKey.currentState.showSnackBar(const SnackBar(
+                        ScaffoldMessenger.of(context).showSnackBar(const SnackBar(
                           content: Text('This would also show a map, if this was not a demo.'),
                         ));
                       },

dev/integration_tests/flutter_gallery/lib/demo/material/bottom_app_bar_demo.dart

@@ -18,7 +18,7 @@ class BottomAppBarDemo extends StatefulWidget {
 // for bottom application bar.
 
 class _BottomAppBarDemoState extends State<BottomAppBarDemo> {
-  static final GlobalKey<ScaffoldState> _scaffoldKey = GlobalKey<ScaffoldState>();
+  static final GlobalKey<ScaffoldMessengerState> _scaffoldMessengerKey = GlobalKey<ScaffoldMessengerState>();
 
   // FAB shape
 
@@ -92,7 +92,7 @@ class _BottomAppBarDemoState extends State<BottomAppBarDemo> {
       "When the Scaffold's floating action button location changes, "
       'the floating action button animates to its new position. '
       'The BottomAppBar adapts its shape appropriately.';
-    _scaffoldKey.currentState.showSnackBar(
+    _scaffoldMessengerKey.currentState.showSnackBar(
       const SnackBar(content: Text(text)),
     );
   }
@@ -139,61 +139,65 @@ class _BottomAppBarDemoState extends State<BottomAppBarDemo> {
 
   @override
   Widget build(BuildContext context) {
-    return Scaffold(
-      key: _scaffoldKey,
-      appBar: AppBar(
-        title: const Text('Bottom app bar'),
-        elevation: 0.0,
-        actions: <Widget>[
-          MaterialDemoDocumentationButton(BottomAppBarDemo.routeName),
-          IconButton(
-            icon: const Icon(Icons.sentiment_very_satisfied, semanticLabel: 'Update shape'),
-            onPressed: () {
-              setState(() {
-                _fabShape = _fabShape == kCircularFab ? kDiamondFab : kCircularFab;
-              });
-            },
+    return ScaffoldMessenger(
+      key: _scaffoldMessengerKey,
+      child: Builder(
+        builder: (BuildContext context) => Scaffold(
+          appBar: AppBar(
+            title: const Text('Bottom app bar'),
+            elevation: 0.0,
+            actions: <Widget>[
+              MaterialDemoDocumentationButton(BottomAppBarDemo.routeName),
+              IconButton(
+                icon: const Icon(Icons.sentiment_very_satisfied, semanticLabel: 'Update shape'),
+                onPressed: () {
+                  setState(() {
+                    _fabShape = _fabShape == kCircularFab ? kDiamondFab : kCircularFab;
+                  });
+                },
+              ),
+            ],
           ),
-        ],
-      ),
-      body: Scrollbar(
-        child: ListView(
-          padding: const EdgeInsets.only(bottom: 88.0),
-          children: <Widget>[
-            const _Heading('FAB Shape'),
+          body: Scrollbar(
+            child: ListView(
+              padding: const EdgeInsets.only(bottom: 88.0),
+              children: <Widget>[
+                const _Heading('FAB Shape'),
 
-            _RadioItem<Widget>(kCircularFab, _fabShape, _onFabShapeChanged),
-            _RadioItem<Widget>(kDiamondFab, _fabShape, _onFabShapeChanged),
-            _RadioItem<Widget>(kNoFab, _fabShape, _onFabShapeChanged),
+                _RadioItem<Widget>(kCircularFab, _fabShape, _onFabShapeChanged),
+                _RadioItem<Widget>(kDiamondFab, _fabShape, _onFabShapeChanged),
+                _RadioItem<Widget>(kNoFab, _fabShape, _onFabShapeChanged),
 
-            const Divider(),
-            const _Heading('Notch'),
+                const Divider(),
+                const _Heading('Notch'),
 
-            _RadioItem<bool>(kShowNotchTrue, _showNotch, _onShowNotchChanged),
-            _RadioItem<bool>(kShowNotchFalse, _showNotch, _onShowNotchChanged),
+                _RadioItem<bool>(kShowNotchTrue, _showNotch, _onShowNotchChanged),
+                _RadioItem<bool>(kShowNotchFalse, _showNotch, _onShowNotchChanged),
 
-            const Divider(),
-            const _Heading('FAB Position'),
+                const Divider(),
+                const _Heading('FAB Position'),
 
-            _RadioItem<FloatingActionButtonLocation>(kFabEndDocked, _fabLocation, _onFabLocationChanged),
-            _RadioItem<FloatingActionButtonLocation>(kFabCenterDocked, _fabLocation, _onFabLocationChanged),
-            _RadioItem<FloatingActionButtonLocation>(kFabEndFloat, _fabLocation, _onFabLocationChanged),
-            _RadioItem<FloatingActionButtonLocation>(kFabCenterFloat, _fabLocation, _onFabLocationChanged),
+                _RadioItem<FloatingActionButtonLocation>(kFabEndDocked, _fabLocation, _onFabLocationChanged),
+                _RadioItem<FloatingActionButtonLocation>(kFabCenterDocked, _fabLocation, _onFabLocationChanged),
+                _RadioItem<FloatingActionButtonLocation>(kFabEndFloat, _fabLocation, _onFabLocationChanged),
+                _RadioItem<FloatingActionButtonLocation>(kFabCenterFloat, _fabLocation, _onFabLocationChanged),
 
-            const Divider(),
-            const _Heading('App bar color'),
+                const Divider(),
+                const _Heading('App bar color'),
 
-            _ColorsItem(kBabColors, _babColor, _onBabColorChanged),
-          ],
+                _ColorsItem(kBabColors, _babColor, _onBabColorChanged),
+              ],
+            ),
+          ),
+          floatingActionButton: _fabShape.value,
+          floatingActionButtonLocation: _fabLocation.value,
+          bottomNavigationBar: _DemoBottomAppBar(
+            color: _babColor,
+            fabLocation: _fabLocation.value,
+            shape: _selectNotch(),
+          ),
         ),
       ),
-      floatingActionButton: _fabShape.value,
-      floatingActionButtonLocation: _fabLocation.value,
-      bottomNavigationBar: _DemoBottomAppBar(
-        color: _babColor,
-        fabLocation: _fabLocation.value,
-        shape: _selectNotch(),
-      ),
     );
   }
 
@@ -364,7 +368,7 @@ class _DemoBottomAppBar extends StatelessWidget {
         IconButton(
           icon: const Icon(Icons.search, semanticLabel: 'show search action',),
           onPressed: () {
-            Scaffold.of(context).showSnackBar(
+            ScaffoldMessenger.of(context).showSnackBar(
               const SnackBar(content: Text('This is a dummy search action.')),
             );
           },
@@ -377,7 +381,7 @@ class _DemoBottomAppBar extends StatelessWidget {
             semanticLabel: 'Show menu actions',
           ),
           onPressed: () {
-            Scaffold.of(context).showSnackBar(
+            ScaffoldMessenger.of(context).showSnackBar(
               const SnackBar(content: Text('This is a dummy menu action.')),
             );
           },

dev/integration_tests/flutter_gallery/lib/demo/material/dialog_demo.dart

@@ -55,7 +55,6 @@ class DialogDemo extends StatefulWidget {
 }
 
 class DialogDemoState extends State<DialogDemo> {
-  final GlobalKey<ScaffoldState> _scaffoldKey = GlobalKey<ScaffoldState>();
 
   TimeOfDay _selectedTime;
 
@@ -73,7 +72,7 @@ class DialogDemoState extends State<DialogDemo> {
     )
     .then<void>((T value) { // The value passed to Navigator.pop() or null.
       if (value != null) {
-        _scaffoldKey.currentState.showSnackBar(SnackBar(
+        ScaffoldMessenger.of(context).showSnackBar(SnackBar(
           content: Text('You selected: $value'),
         ));
       }
@@ -86,7 +85,6 @@ class DialogDemoState extends State<DialogDemo> {
     final TextStyle dialogTextStyle = theme.textTheme.subtitle1.copyWith(color: theme.textTheme.caption.color);
 
     return Scaffold(
-      key: _scaffoldKey,
       appBar: AppBar(
         title: const Text('Dialogs'),
         actions: <Widget>[MaterialDemoDocumentationButton(DialogDemo.routeName)],
@@ -183,7 +181,7 @@ class DialogDemoState extends State<DialogDemo> {
               .then<void>((TimeOfDay value) {
                 if (value != null && value != _selectedTime) {
                   _selectedTime = value;
-                  _scaffoldKey.currentState.showSnackBar(SnackBar(
+                  ScaffoldMessenger.of(context).showSnackBar(SnackBar(
                     content: Text('You selected: ${value.format(context)}'),
                   ));
                 }

dev/integration_tests/flutter_gallery/lib/demo/material/drawer_demo.dart

@@ -75,7 +75,7 @@ class _DrawerDemoState extends State<DrawerDemo> with TickerProviderStateMixin {
 
   void _showNotImplementedMessage() {
     Navigator.pop(context); // Dismiss the drawer.
-    _scaffoldKey.currentState.showSnackBar(const SnackBar(
+    ScaffoldMessenger.of(context).showSnackBar(const SnackBar(
       content: Text("The drawer's items don't do anything"),
     ));
   }

dev/integration_tests/flutter_gallery/lib/demo/material/leave_behind_demo.dart

@@ -42,7 +42,6 @@ class LeaveBehindDemo extends StatefulWidget {
 }
 
 class LeaveBehindDemoState extends State<LeaveBehindDemo> {
-  static final GlobalKey<ScaffoldState> _scaffoldKey = GlobalKey<ScaffoldState>();
   DismissDirection _dismissDirection = DismissDirection.horizontal;
   bool _confirmDismiss = true;
   List<LeaveBehindItem> leaveBehindItems;
@@ -97,7 +96,7 @@ class LeaveBehindDemoState extends State<LeaveBehindDemo> {
     setState(() {
       leaveBehindItems.remove(item);
     });
-    _scaffoldKey.currentState.showSnackBar(SnackBar(
+    ScaffoldMessenger.of(context).showSnackBar(SnackBar(
       content: Text('You archived item ${item.index}'),
       action: SnackBarAction(
         label: 'UNDO',
@@ -110,7 +109,7 @@ class LeaveBehindDemoState extends State<LeaveBehindDemo> {
     setState(() {
       leaveBehindItems.remove(item);
     });
-    _scaffoldKey.currentState.showSnackBar(SnackBar(
+    ScaffoldMessenger.of(context).showSnackBar(SnackBar(
       content: Text('You deleted item ${item.index}'),
       action: SnackBarAction(
         label: 'UNDO',
@@ -146,7 +145,6 @@ class LeaveBehindDemoState extends State<LeaveBehindDemo> {
     }
 
     return Scaffold(
-      key: _scaffoldKey,
       appBar: AppBar(
         title: const Text('Swipe to dismiss'),
         actions: <Widget>[

dev/integration_tests/flutter_gallery/lib/demo/material/menu_demo.dart

@@ -16,7 +16,6 @@ class MenuDemo extends StatefulWidget {
 }
 
 class MenuDemoState extends State<MenuDemo> {
-  final GlobalKey<ScaffoldState> _scaffoldKey = GlobalKey<ScaffoldState>();
 
   final String _simpleValue1 = 'Menu item value one';
   final String _simpleValue2 = 'Menu item value two';
@@ -37,7 +36,7 @@ class MenuDemoState extends State<MenuDemo> {
   }
 
   void showInSnackBar(String value) {
-    _scaffoldKey.currentState.showSnackBar(SnackBar(
+    ScaffoldMessenger.of(context).showSnackBar(SnackBar(
      content: Text(value),
     ));
   }
@@ -62,7 +61,6 @@ class MenuDemoState extends State<MenuDemo> {
   @override
   Widget build(BuildContext context) {
     return Scaffold(
-      key: _scaffoldKey,
       appBar: AppBar(
         title: const Text('Menus'),
         actions: <Widget>[

dev/integration_tests/flutter_gallery/lib/demo/material/overscroll_demo.dart

@@ -20,7 +20,6 @@ class OverscrollDemo extends StatefulWidget {
 }
 
 class OverscrollDemoState extends State<OverscrollDemo> {
-  final GlobalKey<ScaffoldState> _scaffoldKey = GlobalKey<ScaffoldState>();
   final GlobalKey<RefreshIndicatorState> _refreshIndicatorKey = GlobalKey<RefreshIndicatorState>();
   static final List<String> _items = <String>[
     'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N',
@@ -30,7 +29,7 @@ class OverscrollDemoState extends State<OverscrollDemo> {
     final Completer<void> completer = Completer<void>();
     Timer(const Duration(seconds: 3), () { completer.complete(); });
     return completer.future.then<void>((_) {
-      _scaffoldKey.currentState?.showSnackBar(SnackBar(
+      ScaffoldMessenger.of(context).showSnackBar(SnackBar(
         content: const Text('Refresh complete'),
         action: SnackBarAction(
           label: 'RETRY',
@@ -45,7 +44,6 @@ class OverscrollDemoState extends State<OverscrollDemo> {
   @override
   Widget build(BuildContext context) {
     return Scaffold(
-      key: _scaffoldKey,
       appBar: AppBar(
         title: const Text('Pull to refresh'),
         actions: <Widget>[

dev/integration_tests/flutter_gallery/lib/demo/material/snack_bar_demo.dart

@@ -44,12 +44,12 @@ class _SnackBarDemoState extends State<SnackBarDemo> {
               child: const Text('SHOW A SNACKBAR'),
               onPressed: () {
                 final int thisSnackBarIndex = _snackBarIndex++;
-                Scaffold.of(context).showSnackBar(SnackBar(
+                ScaffoldMessenger.of(context).showSnackBar(SnackBar(
                   content: Text('This is snackbar #$thisSnackBarIndex.'),
                   action: SnackBarAction(
                     label: 'ACTION',
                     onPressed: () {
-                      Scaffold.of(context).showSnackBar(SnackBar(
+                      ScaffoldMessenger.of(context).showSnackBar(SnackBar(
                         content: Text("You pressed snackbar $thisSnackBarIndex's action."),
                       ));
                     },

dev/integration_tests/flutter_gallery/lib/demo/material/text_form_field_demo.dart

@@ -83,12 +83,11 @@ class _PasswordFieldState extends State<PasswordField> {
 }
 
 class TextFormFieldDemoState extends State<TextFormFieldDemo> {
-  final GlobalKey<ScaffoldState> _scaffoldKey = GlobalKey<ScaffoldState>();
 
   PersonData person = PersonData();
 
   void showInSnackBar(String value) {
-    _scaffoldKey.currentState.showSnackBar(SnackBar(
+    ScaffoldMessenger.of(context).showSnackBar(SnackBar(
       content: Text(value),
     ));
   }
@@ -168,7 +167,6 @@ class TextFormFieldDemoState extends State<TextFormFieldDemo> {
   Widget build(BuildContext context) {
     return Scaffold(
       drawerDragStartBehavior: DragStartBehavior.down,
-      key: _scaffoldKey,
       appBar: AppBar(
         title: const Text('Text fields'),
         actions: <Widget>[MaterialDemoDocumentationButton(TextFormFieldDemo.routeName)],

dev/integration_tests/flutter_gallery/lib/demo/material/tooltip_demo.dart

@@ -52,7 +52,7 @@ class TooltipDemo extends StatelessWidget {
                     color: theme.iconTheme.color,
                     tooltip: 'Place a phone call',
                     onPressed: () {
-                      Scaffold.of(context).showSnackBar(const SnackBar(
+                      ScaffoldMessenger.of(context).showSnackBar(const SnackBar(
                          content: Text('That was an ordinary tap.'),
                       ));
                     },

dev/integration_tests/flutter_gallery/lib/demo/pesto_demo.dart

@@ -73,7 +73,6 @@ class RecipeGridPage extends StatefulWidget {
 }
 
 class _RecipeGridPageState extends State<RecipeGridPage> {
-  final GlobalKey<ScaffoldState> scaffoldKey = GlobalKey<ScaffoldState>();
 
   @override
   Widget build(BuildContext context) {
@@ -81,11 +80,10 @@ class _RecipeGridPageState extends State<RecipeGridPage> {
     return Theme(
       data: _kTheme.copyWith(platform: Theme.of(context).platform),
       child: Scaffold(
-        key: scaffoldKey,
         floatingActionButton: FloatingActionButton(
           child: const Icon(Icons.edit),
           onPressed: () {
-            scaffoldKey.currentState.showSnackBar(const SnackBar(
+            ScaffoldMessenger.of(context).showSnackBar(const SnackBar(
               content: Text('Not supported.'),
             ));
           },
@@ -110,7 +108,7 @@ class _RecipeGridPageState extends State<RecipeGridPage> {
           icon: const Icon(Icons.search),
           tooltip: 'Search',
           onPressed: () {
-            scaffoldKey.currentState.showSnackBar(const SnackBar(
+            ScaffoldMessenger.of(context).showSnackBar(const SnackBar(
               content: Text('Not supported.'),
             ));
           },
@@ -322,7 +320,6 @@ class RecipePage extends StatefulWidget {
 }
 
 class _RecipePageState extends State<RecipePage> {
-  final GlobalKey<ScaffoldState> _scaffoldKey = GlobalKey<ScaffoldState>();
   final TextStyle menuItemStyle = const PestoStyle(fontSize: 15.0, color: Colors.black54, height: 24.0/15.0);
 
   double _getAppBarHeight(BuildContext context) => MediaQuery.of(context).size.height * 0.3;
@@ -337,7 +334,6 @@ class _RecipePageState extends State<RecipePage> {
     final bool fullWidth = screenSize.width < _kRecipePageMaxWidth;
     final bool isFavorite = _favoriteRecipes.contains(widget.recipe);
     return Scaffold(
-      key: _scaffoldKey,
       body: Stack(
         children: <Widget>[
           Positioned(

dev/integration_tests/flutter_gallery/lib/demo/video_demo.dart

@@ -266,12 +266,10 @@ class ConnectivityOverlay extends StatefulWidget {
   const ConnectivityOverlay({
     this.child,
     this.connectedCompleter,
-    this.scaffoldKey,
   });
 
   final Widget child;
   final Completer<void> connectedCompleter;
-  final GlobalKey<ScaffoldState> scaffoldKey;
 
   @override
   _ConnectivityOverlayState createState() => _ConnectivityOverlayState();
@@ -321,7 +319,7 @@ class _ConnectivityOverlayState extends State<ConnectivityOverlay> {
           return;
         }
         if (connectivityResult == ConnectivityResult.none) {
-          widget.scaffoldKey.currentState.showSnackBar(errorSnackBar);
+          ScaffoldMessenger.of(context).showSnackBar(errorSnackBar);
         } else {
           if (!widget.connectedCompleter.isCompleted) {
             widget.connectedCompleter.complete(null);
@@ -368,7 +366,6 @@ class _VideoDemoState extends State<VideoDemo> with SingleTickerProviderStateMix
   static const String beeUri = 'https://flutter.github.io/assets-for-api-docs/assets/videos/bee.mp4';
   final VideoPlayerController beeController = VideoPlayerController.network(beeUri);
 
-  final GlobalKey<ScaffoldState> scaffoldKey = GlobalKey<ScaffoldState>();
   final Completer<void> connectedCompleter = Completer<void>();
   bool isSupported = true;
   bool isDisposed = false;
@@ -410,7 +407,6 @@ class _VideoDemoState extends State<VideoDemo> with SingleTickerProviderStateMix
   @override
   Widget build(BuildContext context) {
     return Scaffold(
-      key: scaffoldKey,
       appBar: AppBar(
         title: const Text('Videos'),
       ),
@@ -433,7 +429,6 @@ class _VideoDemoState extends State<VideoDemo> with SingleTickerProviderStateMix
               ),
             ),
             connectedCompleter: connectedCompleter,
-            scaffoldKey: scaffoldKey,
           )
         : const Center(
             child: Text(

dev/integration_tests/hybrid_android_views/lib/motion_events_page.dart

@@ -169,7 +169,7 @@ class MotionEventsBodyState extends State<MotionEventsBody> {
   }
 
   void showMessage(BuildContext context, String message) {
-    Scaffold.of(context).showSnackBar(SnackBar(
+    ScaffoldMessenger.of(context).showSnackBar(SnackBar(
       content: Text(message),
       duration: const Duration(seconds: 3),
     ));