Split helper classes from main example widget.

Move the `WebView` and related `WebViewController` classes from the
main.dart into a separate web_view.dart file.

Author: mvanbeusekom

packages/webview_flutter/webview_flutter_android/CHANGELOG.md

@@ -1,4 +1,4 @@
-## 0.0.1
+## 2.0.13
 
 * Extract Android implementation from `webview_flutter`.
 

packages/webview_flutter/webview_flutter_android/example/integration_test/webview_flutter_test.dart

@@ -14,13 +14,15 @@ import 'package:flutter_test/flutter_test.dart';
 import 'package:integration_test/integration_test.dart';
 import 'package:webview_flutter_android/webview_android.dart';
 import 'package:webview_flutter_android/webview_surface_android.dart';
-import 'package:webview_flutter_android_example/main.dart';
+import 'package:webview_flutter_android_example/navigation_decision.dart';
+import 'package:webview_flutter_android_example/navigation_request.dart';
+import 'package:webview_flutter_android_example/web_view.dart';
 import 'package:webview_flutter_platform_interface/webview_flutter_platform_interface.dart';
 
 void main() {
   IntegrationTestWidgetsFlutterBinding.ensureInitialized();
 
-  const bool _skipDueIssue86757 = true;
+  const bool _skipDueToIssue86757 = true;
 
   // TODO(bparrishMines): skipped due to https://github.com/flutter/flutter/issues/86757.
   testWidgets('initialUrl', (WidgetTester tester) async {
@@ -43,7 +45,7 @@ void main() {
     final WebViewController controller = await controllerCompleter.future;
     final String? currentUrl = await controller.currentUrl();
     expect(currentUrl, 'https://flutter.dev/');
-  }, skip: _skipDueIssue86757);
+  }, skip: _skipDueToIssue86757);
 
   // TODO(bparrishMines): skipped due to https://github.com/flutter/flutter/issues/86757.
   testWidgets('loadUrl', (WidgetTester tester) async {
@@ -65,7 +67,7 @@ void main() {
     await controller.loadUrl('https://www.google.com/');
     final String? currentUrl = await controller.currentUrl();
     expect(currentUrl, 'https://www.google.com/');
-  }, skip: _skipDueIssue86757);
+  }, skip: _skipDueToIssue86757);
 
   // TODO(bparrishMines): skipped due to https://github.com/flutter/flutter/issues/86757.
   testWidgets('loadUrl with headers', (WidgetTester tester) async {
@@ -107,7 +109,7 @@ void main() {
     final String content = await controller
         .evaluateJavascript('document.documentElement.innerText');
     expect(content.contains('flutter_test_header'), isTrue);
-  }, skip: _skipDueIssue86757);
+  }, skip: _skipDueToIssue86757);
 
   // TODO(bparrishMines): skipped due to https://github.com/flutter/flutter/issues/86757.
   testWidgets('JavaScriptChannel', (WidgetTester tester) async {
@@ -156,7 +158,7 @@ void main() {
     // https://github.com/flutter/flutter/issues/66318
     await controller.evaluateJavascript('Echo.postMessage("hello");1;');
     expect(messagesReceived, equals(<String>['hello']));
-  }, skip: _skipDueIssue86757);
+  }, skip: _skipDueToIssue86757);
 
   testWidgets('resize webview', (WidgetTester tester) async {
     final String resizeTest = '''
@@ -334,7 +336,7 @@ void main() {
 
     final String customUserAgent2 = await _getUserAgent(controller);
     expect(customUserAgent2, defaultPlatformUserAgent);
-  }, skip: _skipDueIssue86757);
+  }, skip: _skipDueToIssue86757);
 
   group('Video playback policy', () {
     late String videoTestBase64;
@@ -831,7 +833,7 @@ void main() {
       scrollPosY = await controller.getScrollY();
       expect(scrollPosX, X_SCROLL * 2);
       expect(scrollPosY, Y_SCROLL * 2);
-    }, skip: _skipDueIssue86757);
+    }, skip: _skipDueToIssue86757);
   });
 
   group('SurfaceAndroidWebView', () {
@@ -910,7 +912,7 @@ void main() {
       scrollPosY = await controller.getScrollY();
       expect(X_SCROLL * 2, scrollPosX);
       expect(Y_SCROLL * 2, scrollPosY);
-    }, skip: _skipDueIssue86757);
+    }, skip: _skipDueToIssue86757);
 
     // TODO(bparrishMines): skipped due to https://github.com/flutter/flutter/issues/86757.
     testWidgets('inputs are scrolled into view when focused',
@@ -1016,7 +1018,7 @@ void main() {
           lastInputClientRectRelativeToViewport['right'] <=
               viewportRectRelativeToViewport['right'],
           isTrue);
-    }, skip: _skipDueIssue86757);
+    }, skip: _skipDueToIssue86757);
   });
 
   group('NavigationDelegate', () {
@@ -1281,7 +1283,7 @@ void main() {
     expect(currentUrl, 'https://flutter.dev/');
   },
       // Flaky on Android: https://github.com/flutter/flutter/issues/86757
-      skip: _skipDueIssue86757);
+      skip: _skipDueToIssue86757);
 
   // TODO(bparrishMines): skipped due to https://github.com/flutter/flutter/issues/86757.
   testWidgets(
@@ -1322,7 +1324,7 @@ void main() {
       await pageLoaded.future;
       expect(controller.currentUrl(), completion('https://flutter.dev/'));
     },
-    skip: _skipDueIssue86757,
+    skip: _skipDueToIssue86757,
   );
 
   testWidgets(