Add sample menu for payment request

Author: mataku

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

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