Create readme_excerpts.dart for snippets in README

Author: mataku

packages/webview_flutter/webview_flutter_android/README.md

@@ -57,7 +57,7 @@ import io.flutter.plugins.webviewflutter.WebViewFlutterAndroidExternalApi;
 The Payment Request API can be enabled by calling `AndroidWebViewController.setPaymentRequestEnabled` after
 checking `AndroidWebViewController.isWebViewFeatureSupported`.
 
-<?code-excerpt "example/lib/main.dart (payment_request_example)"?>
+<?code-excerpt "example/lib/readme_excerpts.dart (payment_request_example)"?>
 ```dart
 final bool paymentRequestEnabled = await androidController
     .isWebViewFeatureSupported(WebViewFeatureType.paymentRequest);

packages/webview_flutter/webview_flutter_android/example/lib/main.dart

@@ -350,7 +350,6 @@ enum MenuOptions {
   basicAuthentication,
   javaScriptAlert,
   viewportMeta,
-  checkWebViewPaymentRequestFeatureEnabled,
 }
 
 class SampleMenu extends StatelessWidget {
@@ -408,8 +407,6 @@ class SampleMenu extends StatelessWidget {
             _onJavaScriptAlertExample(context);
           case MenuOptions.viewportMeta:
             _onViewportMetaExample();
-          case MenuOptions.checkWebViewPaymentRequestFeatureEnabled:
-            _onWebViewFeatureExample(context);
         }
       },
       itemBuilder: (BuildContext context) => <PopupMenuItem<MenuOptions>>[
@@ -486,10 +483,6 @@ class SampleMenu extends StatelessWidget {
           value: MenuOptions.viewportMeta,
           child: Text('Viewport meta example'),
         ),
-        const PopupMenuItem<MenuOptions>(
-          value: MenuOptions.checkWebViewPaymentRequestFeatureEnabled,
-          child: Text('WebView Feature Example'),
-        ),
       ],
     );
   }
@@ -790,24 +783,6 @@ class SampleMenu extends StatelessWidget {
   Future<void> _onViewportMetaExample() {
     return webViewController.loadHtmlString(kViewportMetaPage);
   }
-
-  Future<void> _onWebViewFeatureExample(BuildContext context) async {
-    final AndroidWebViewController androidController =
-        webViewController as AndroidWebViewController;
-    // #docregion payment_request_example
-    final bool paymentRequestEnabled = await androidController
-        .isWebViewFeatureSupported(WebViewFeatureType.paymentRequest);
-
-    if (paymentRequestEnabled) {
-      await androidController.setPaymentRequestEnabled(true);
-    }
-    // #enddocregion payment_request_example
-    if (context.mounted) {
-      ScaffoldMessenger.of(context).showSnackBar(SnackBar(
-        content: Text('Payment Request API supported: $paymentRequestEnabled'),
-      ));
-    }
-  }
 }
 
 class NavigationControls extends StatelessWidget {

packages/webview_flutter/webview_flutter_android/example/lib/readme_excerpts.dart

@@ -0,0 +1,22 @@
+// Copyright 2013 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 'package:webview_flutter_android/webview_flutter_android.dart';
+import 'package:webview_flutter_platform_interface/webview_flutter_platform_interface.dart';
+
+/// Example function for README demonstration of Payment Request API.
+Future<void> enablePaymentRequest() async {
+  final PlatformWebViewController controller =
+      PlatformWebViewController(AndroidWebViewControllerCreationParams());
+  final AndroidWebViewController androidController =
+      controller as AndroidWebViewController;
+  // #docregion payment_request_example
+  final bool paymentRequestEnabled = await androidController
+      .isWebViewFeatureSupported(WebViewFeatureType.paymentRequest);
+
+  if (paymentRequestEnabled) {
+    await androidController.setPaymentRequestEnabled(true);
+  }
+  // #enddocregion payment_request_example
+}