Wide gamut and platform view integration test. (#138837)

In https://github.com/flutter/engine/pull/48190 I discovered that overlay surfaces were not constructed with wide gamut settings. This adds a test that will fail until this is fixed.

dev/integration_tests/wide_gamut_test/integration_test/app_test.dart

@@ -166,6 +166,15 @@ void main() {
       app.run(app.Setup.drawnImage);
       await tester.pumpAndSettle(const Duration(seconds: 2));
 
+      const MethodChannel channel = MethodChannel('flutter/screenshot');
+      final List<Object?> result =
+          await channel.invokeMethod('test') as List<Object?>;
+      expect(_findColor(result, <double>[0.0, 1.0, 0.0]), isTrue);
+    });
+    testWidgets('draw image with wide gamut works ontop of platform view with blur', (WidgetTester tester) async {
+      app.run(app.Setup.drawnImageAndPlatformView);
+      await tester.pumpAndSettle(const Duration(seconds: 2));
+
       const MethodChannel channel = MethodChannel('flutter/screenshot');
       final List<Object?> result =
           await channel.invokeMethod('test') as List<Object?>;

dev/integration_tests/wide_gamut_test/ios/Runner/AppDelegate.swift

+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import UIKit
+import Flutter
+
+@UIApplicationMain
+@objc class AppDelegate: FlutterAppDelegate {
+  override func application(
+    _ application: UIApplication,
+    didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
+  ) -> Bool {
+    GeneratedPluginRegistrant.register(with: self)
+
+    var registrar = self.registrar(forPlugin: "plugin-name")
+    let factory = FLNativeViewFactory(messenger: registrar!.messenger())
+    self.registrar(forPlugin: "<plugin-name>")!.register(
+        factory,
+        withId: "<dummy-view>")
+
+    return super.application(application, didFinishLaunchingWithOptions: launchOptions)
+  }
+}

dev/integration_tests/wide_gamut_test/ios/Runner/DummyPlatformView.swift

+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import Foundation
+
+import Flutter
+import UIKit
+
+class FLNativeViewFactory: NSObject, FlutterPlatformViewFactory {
+    private var messenger: FlutterBinaryMessenger
+
+    init(messenger: FlutterBinaryMessenger) {
+        self.messenger = messenger
+        super.init()
+    }
+
+    func create(
+        withFrame frame: CGRect,
+        viewIdentifier viewId: Int64,
+        arguments args: Any?
+    ) -> FlutterPlatformView {
+        return FLNativeView(
+            frame: frame,
+            viewIdentifier: viewId,
+            arguments: args,
+            binaryMessenger: messenger)
+    }
+
+    public func createArgsCodec() -> FlutterMessageCodec & NSObjectProtocol {
+          return FlutterStandardMessageCodec.sharedInstance()
+    }
+}
+
+class SolidColorView: UIView {
+  override init(frame: CGRect) {
+    super.init(frame: frame)
+    setupView()
+  }
+
+  required init?(coder aDecoder: NSCoder) {
+    super.init(coder: aDecoder)
+    setupView()
+  }
+
+  private func setupView() {
+    backgroundColor = .blue
+  }
+}
+
+
+class FLNativeView: NSObject, FlutterPlatformView {
+    private var view: UIView
+
+    init(
+        frame: CGRect,
+        viewIdentifier viewId: Int64,
+        arguments args: Any?,
+        binaryMessenger messenger: FlutterBinaryMessenger?
+    ) {
+        view = SolidColorView()
+        super.init()
+    }
+
+    func view() -> UIView {
+        return view
+    }
+}

dev/integration_tests/wide_gamut_test/lib/main.dart

@@ -145,6 +145,7 @@ enum Setup {
   canvasSaveLayer,
   blur,
   drawnImage,
+  drawnImageAndPlatformView
 }
 
 void run(Setup setup) {
@@ -244,6 +245,19 @@ Future<ui.Image> _loadImage() async {
   return (await codec.getNextFrame()).image;
 }
 
+class DummyPlatformView extends StatelessWidget {
+  const DummyPlatformView({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return const SizedBox(
+      width: 400,
+      height: 400,
+      child: UiKitView(viewType: '<dummy-view>'),
+    );
+  }
+}
+
 class MyHomePage extends StatefulWidget {
   const MyHomePage(this.setup, {super.key, required this.title});
 
@@ -285,6 +299,14 @@ class _MyHomePageState extends State<MyHomePage> {
         imageWidget = Image.memory(base64Decode(_displayP3Logo));
       case Setup.drawnImage:
         imageWidget = CustomPaint(painter: _SaveLayerDrawer(_image));
+      case Setup.drawnImageAndPlatformView:
+        imageWidget = Stack(
+          children: <Widget>[
+            const DummyPlatformView(),
+            Image.memory(base64Decode(_displayP3Logo)),
+            BackdropFilter(filter: ui.ImageFilter.blur(sigmaX: 6, sigmaY: 6), child: const SizedBox(width: 400, height: 400)),
+          ],
+        );
       case Setup.canvasSaveLayer:
         imageWidget = CustomPaint(painter: _SaveLayerDrawer(_image));
       case Setup.blur: