Scenario nnbd (flutter#27365)

* Revert "Revert "NNBD migration for scenario_app (flutter#27362)" (flutter#27364)"

This reverts commit 57720b2.

* analysis issues

* no sound null safety because frontend_server is not

testing/scenario_app/lib/main.dart

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.6
+
 import 'dart:convert';
 import 'dart:developer' as developer;
 import 'dart:io';
@@ -27,7 +27,7 @@ void main() {
 }
 
 void _handleDriverMessage(Map<String, dynamic> call) {
-  final String methodName = call['method'] as String;
+  final String? methodName = call['method'] as String?;
   switch (methodName) {
     case 'set_scenario':
       assert(call['args'] != null);
@@ -39,7 +39,7 @@ void _handleDriverMessage(Map<String, dynamic> call) {
 }
 
 Future<void> _handlePlatformMessage(
-    String name, ByteData data, PlatformMessageResponseCallback callback) async {
+    String name, ByteData? data, PlatformMessageResponseCallback? callback) async {
   if (data != null) {
     print('$name = ${utf8.decode(data.buffer.asUint8List())}');
   } else {
@@ -48,11 +48,11 @@ Future<void> _handlePlatformMessage(
 
   switch (name) {
     case 'driver':
-      _handleDriverMessage(json.decode(utf8.decode(data.buffer.asUint8List())) as Map<String, dynamic>);
+      _handleDriverMessage(json.decode(utf8.decode(data!.buffer.asUint8List())) as Map<String, dynamic>);
     break;
     case 'write_timeline':
       final String timelineData = await _getTimelineData();
-      callback(Uint8List.fromList(utf8.encode(timelineData)).buffer.asByteData());
+      callback!(Uint8List.fromList(utf8.encode(timelineData)).buffer.asByteData());
     break;
     default:
       currentScenario?.onPlatformMessage(name, data, callback);
@@ -61,7 +61,7 @@ Future<void> _handlePlatformMessage(
 
 Future<String> _getTimelineData() async {
   final developer.ServiceProtocolInfo info = await developer.Service.getInfo();
-  final Uri vmServiceTimelineUri = info.serverUri.resolve('getVMTimeline');
+  final Uri vmServiceTimelineUri = info.serverUri!.resolve('getVMTimeline');
   final Map<String, dynamic> vmServiceTimelineJson = await _getJson(vmServiceTimelineUri);
   final Map<String, dynamic> vmServiceResult = vmServiceTimelineJson['result'] as Map<String, dynamic>;
   return json.encode(<String, dynamic>{

testing/scenario_app/lib/src/animated_color_square.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.6
 import 'dart:math' as math;
 import 'dart:ui';
 
@@ -77,19 +76,19 @@ class AnimatedColorSquareScenario extends Scenario {
 }
 
 class _NumberSwinger<T extends num> {
-  _NumberSwinger(this._begin, this._end, [this._current])
+  _NumberSwinger(this._begin, this._end, [T? current])
       : assert(_begin != null),
         assert(_end != null),
         _up = _begin < _end {
-    _current ??= _begin;
+    _current = current ?? _begin;
   }
 
   final T _begin;
   final T _end;
 
   /// The current value of the swinger.
   T get current => _current;
-  T _current;
+  late T _current;
 
   bool _up;
 

testing/scenario_app/lib/src/bogus_font_text.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.6
 import 'dart:ui';
 
 import 'channel_util.dart';

testing/scenario_app/lib/src/channel_util.dart

@@ -2,21 +2,17 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.6
-
 import 'dart:convert';
 import 'dart:ui';
 
-import 'package:meta/meta.dart';
-
 /// Util method to replicate the behavior of a `MethodChannel` in the Flutter
 /// framework.
 void sendJsonMethodCall({
-  @required PlatformDispatcher dispatcher,
-  @required String channel,
-  @required String method,
+  required PlatformDispatcher dispatcher,
+  required String channel,
+  required String method,
   dynamic arguments,
-  PlatformMessageResponseCallback callback,
+  PlatformMessageResponseCallback? callback,
 }) {
   sendJsonMessage(
     dispatcher: dispatcher,
@@ -30,10 +26,10 @@ void sendJsonMethodCall({
 
 /// Send a JSON message over a channel.
 void sendJsonMessage({
-  @required PlatformDispatcher dispatcher,
-  @required String channel,
-  @required Map<String, dynamic> json,
-  PlatformMessageResponseCallback callback,
+  required PlatformDispatcher dispatcher,
+  required String channel,
+  required Map<String, dynamic> json,
+  PlatformMessageResponseCallback? callback,
 }) {
   dispatcher.sendPlatformMessage(
     channel,

testing/scenario_app/lib/src/initial_route_reply.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.6
 import 'dart:ui';
 
 import 'channel_util.dart';

testing/scenario_app/lib/src/locale_initialization.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.6
-
 import 'dart:typed_data';
 import 'dart:ui';
 

testing/scenario_app/lib/src/platform_echo_mixin.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.6
 import 'dart:typed_data';
 import 'dart:ui';
 
@@ -13,8 +12,8 @@ mixin PlatformEchoMixin on Scenario {
   @override
   void onPlatformMessage(
     String name,
-    ByteData data,
-    PlatformMessageResponseCallback callback,
+    ByteData? data,
+    PlatformMessageResponseCallback? callback,
   ) {
     window.sendPlatformMessage(name, data, null);
   }

testing/scenario_app/lib/src/platform_view.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.6
 import 'dart:convert';
 import 'dart:io';
 import 'dart:typed_data';
@@ -33,7 +32,7 @@ class PlatformViewScenario extends Scenario with _BasePlatformViewScenarioMixin
   /// Creates the PlatformView scenario.
   ///
   /// The [dispatcher] parameter must not be null.
-  PlatformViewScenario(PlatformDispatcher dispatcher, String text, { this.id })
+  PlatformViewScenario(PlatformDispatcher dispatcher, String text, { required this.id })
       : assert(dispatcher != null),
         super(dispatcher) {
     createPlatformView(dispatcher, text, id);
@@ -58,7 +57,7 @@ class NonFullScreenFlutterViewPlatformViewScenario extends Scenario
   /// The [dispatcher] parameter must not be null.
   NonFullScreenFlutterViewPlatformViewScenario(
       PlatformDispatcher dispatcher, String text,
-      {this.id})
+      {required this.id})
       : assert(dispatcher != null),
         super(dispatcher) {
     createPlatformView(dispatcher, text, id);
@@ -80,7 +79,7 @@ class PlatformViewNoOverlayIntersectionScenario extends Scenario with _BasePlatf
   /// Creates the PlatformView scenario.
   ///
   /// The [dispatcher] parameter must not be null.
-  PlatformViewNoOverlayIntersectionScenario(PlatformDispatcher dispatcher, String text, { this.id })
+  PlatformViewNoOverlayIntersectionScenario(PlatformDispatcher dispatcher, String text, { required this.id })
       : assert(dispatcher != null),
         super(dispatcher) {
     createPlatformView(dispatcher, text, id);
@@ -106,7 +105,7 @@ class PlatformViewPartialIntersectionScenario extends Scenario with _BasePlatfor
   /// Creates the PlatformView scenario.
   ///
   /// The [dispatcher] parameter must not be null.
-  PlatformViewPartialIntersectionScenario(PlatformDispatcher dispatcher, String text, { this.id })
+  PlatformViewPartialIntersectionScenario(PlatformDispatcher dispatcher, String text, { required this.id })
       : assert(dispatcher != null),
         super(dispatcher) {
     createPlatformView(dispatcher, text, id);
@@ -132,7 +131,7 @@ class PlatformViewTwoIntersectingOverlaysScenario extends Scenario with _BasePla
   /// Creates the PlatformView scenario.
   ///
   /// The [dispatcher] parameter must not be null.
-  PlatformViewTwoIntersectingOverlaysScenario(PlatformDispatcher dispatcher, String text, { this.id })
+  PlatformViewTwoIntersectingOverlaysScenario(PlatformDispatcher dispatcher, String text, { required this.id })
       : assert(dispatcher != null),
         super(dispatcher) {
     createPlatformView(dispatcher, text, id);
@@ -171,7 +170,7 @@ class PlatformViewOneOverlayTwoIntersectingOverlaysScenario extends Scenario wit
   /// Creates the PlatformView scenario.
   ///
   /// The [dispatcher] parameter must not be null.
-  PlatformViewOneOverlayTwoIntersectingOverlaysScenario(PlatformDispatcher dispatcher, String text, { this.id })
+  PlatformViewOneOverlayTwoIntersectingOverlaysScenario(PlatformDispatcher dispatcher, String text, { required this.id })
       : assert(dispatcher != null),
         super(dispatcher) {
     createPlatformView(dispatcher, text, id);
@@ -215,7 +214,7 @@ class MultiPlatformViewWithoutOverlaysScenario extends Scenario with _BasePlatfo
   /// Creates the PlatformView scenario.
   ///
   /// The [dispatcher] parameter must not be null.
-  MultiPlatformViewWithoutOverlaysScenario(PlatformDispatcher dispatcher, String text, { this.firstId, this.secondId })
+  MultiPlatformViewWithoutOverlaysScenario(PlatformDispatcher dispatcher, String text, { required this.firstId, required this.secondId })
       : assert(dispatcher != null),
         super(dispatcher) {
     createPlatformView(dispatcher, text, firstId);
@@ -259,7 +258,7 @@ class PlatformViewMaxOverlaysScenario extends Scenario with _BasePlatformViewSce
   /// Creates the PlatformView scenario.
   ///
   /// The [dispatcher] parameter must not be null.
-  PlatformViewMaxOverlaysScenario(PlatformDispatcher dispatcher, String text, { this.id })
+  PlatformViewMaxOverlaysScenario(PlatformDispatcher dispatcher, String text, { required this.id })
       : assert(dispatcher != null),
         super(dispatcher) {
     createPlatformView(dispatcher, text, id);
@@ -308,7 +307,7 @@ class MultiPlatformViewScenario extends Scenario with _BasePlatformViewScenarioM
   /// Creates the PlatformView scenario.
   ///
   /// The [dispatcher] parameter must not be null.
-  MultiPlatformViewScenario(PlatformDispatcher dispatcher, {this.firstId, this.secondId})
+  MultiPlatformViewScenario(PlatformDispatcher dispatcher, {required this.firstId, required this.secondId})
       : assert(dispatcher != null),
         super(dispatcher) {
     createPlatformView(dispatcher, 'platform view 1', firstId);
@@ -342,7 +341,7 @@ class MultiPlatformViewBackgroundForegroundScenario extends Scenario with _BaseP
   /// Creates the PlatformView scenario.
   ///
   /// The [dispatcher] parameter must not be null.
-  MultiPlatformViewBackgroundForegroundScenario(PlatformDispatcher dispatcher, {this.firstId, this.secondId})
+  MultiPlatformViewBackgroundForegroundScenario(PlatformDispatcher dispatcher, {required this.firstId, required this.secondId})
       : assert(dispatcher != null),
         super(dispatcher) {
     _nextFrame = _firstFrame;
@@ -361,7 +360,7 @@ class MultiPlatformViewBackgroundForegroundScenario extends Scenario with _BaseP
     _nextFrame();
   }
 
-  VoidCallback _nextFrame;
+  late VoidCallback _nextFrame;
 
   void _firstFrame() {
     final SceneBuilder builder = SceneBuilder();
@@ -407,13 +406,13 @@ class MultiPlatformViewBackgroundForegroundScenario extends Scenario with _BaseP
   @override
   void onPlatformMessage(
       String name,
-      ByteData data,
-      PlatformMessageResponseCallback callback,
+      ByteData? data,
+      PlatformMessageResponseCallback? callback,
       ) {
     if (name != 'flutter/lifecycle') {
       return;
     }
-    final String message = utf8.decode(data.buffer.asUint8List());
+    final String message = utf8.decode(data!.buffer.asUint8List());
     if (_lastLifecycleState == 'AppLifecycleState.inactive' && message == 'AppLifecycleState.resumed') {
       _nextFrame = _secondFrame;
       window.scheduleFrame();
@@ -426,7 +425,7 @@ class MultiPlatformViewBackgroundForegroundScenario extends Scenario with _BaseP
 /// Platform view with clip rect.
 class PlatformViewClipRectScenario extends Scenario with _BasePlatformViewScenarioMixin {
   /// Constructs a platform view with clip rect scenario.
-  PlatformViewClipRectScenario(PlatformDispatcher dispatcher, String text, { this.id })
+  PlatformViewClipRectScenario(PlatformDispatcher dispatcher, String text, { required this.id })
       : assert(dispatcher != null),
         super(dispatcher) {
     createPlatformView(dispatcher, text, id);
@@ -524,15 +523,10 @@ class PlatformViewOpacityScenario extends PlatformViewScenario {
 /// A simple platform view for testing touch events from iOS.
 class PlatformViewForTouchIOSScenario extends Scenario
     with _BasePlatformViewScenarioMixin {
-
-  int _viewId;
-  bool _accept;
-
-  VoidCallback _nextFrame;
   /// Creates the PlatformView scenario.
   ///
   /// The [dispatcher] parameter must not be null.
-  PlatformViewForTouchIOSScenario(PlatformDispatcher dispatcher, String text, {int id = 0, bool accept, bool rejectUntilTouchesEnded = false})
+  PlatformViewForTouchIOSScenario(PlatformDispatcher dispatcher, String text, {int id = 0, required bool accept, bool rejectUntilTouchesEnded = false})
       : assert(dispatcher != null),
        _accept = accept,
       _viewId = id,
@@ -545,6 +539,10 @@ class PlatformViewForTouchIOSScenario extends Scenario
     _nextFrame = _firstFrame;
   }
 
+  int _viewId;
+  bool _accept;
+  late VoidCallback _nextFrame;
+
   @override
   void onBeginFrame(Duration duration) {
     _nextFrame();
@@ -587,7 +585,7 @@ class PlatformViewForTouchIOSScenario extends Scenario
     window.sendPlatformMessage(
       'flutter/platform_views',
       message.buffer.asByteData(),
-      (ByteData response) {},
+      (ByteData? response) {},
     );
     }
 
@@ -622,10 +620,10 @@ class PlatformViewWithContinuousTexture extends PlatformViewScenario {
 }
 
 mixin _BasePlatformViewScenarioMixin on Scenario {
-  int _textureId;
+  int? _textureId;
 
   bool get usesAndroidHybridComposition {
-    return (scenarioParams['use_android_view'] as bool) == true;
+    return (scenarioParams['use_android_view'] as bool?) == true;
   }
 
   /// Construct the platform view related scenario
@@ -702,7 +700,7 @@ mixin _BasePlatformViewScenarioMixin on Scenario {
     dispatcher.sendPlatformMessage(
       'flutter/platform_views',
       message.buffer.asByteData(),
-      (ByteData response) {
+      (ByteData? response) {
         if (response != null && Platform.isAndroid && !usesAndroidHybridComposition) {
           // Envelope.
           _textureId = response.getUint8(0);
@@ -723,7 +721,7 @@ mixin _BasePlatformViewScenarioMixin on Scenario {
       if (usesAndroidHybridComposition) {
         sceneBuilder.addPlatformView(viewId, width: width, height: height);
       } else if (_textureId != null) {
-        sceneBuilder.addTexture(_textureId, width: width, height: height);
+        sceneBuilder.addTexture(_textureId!, width: width, height: height);
       }
     } else {
       throw UnsupportedError('Platform ${Platform.operatingSystem} is not supported');
@@ -734,7 +732,7 @@ mixin _BasePlatformViewScenarioMixin on Scenario {
   void finishBuilderByAddingPlatformViewAndPicture(
     SceneBuilder sceneBuilder,
     int viewId, {
-    Offset overlayOffset,
+    Offset? overlayOffset,
   }) {
     overlayOffset ??= const Offset(50, 50);
     _addPlatformViewToScene(