PaymentApp: Implement invokePaymentApp() in renderer side.

content/renderer/service_worker/service_worker_context_client.h

Index: content/renderer/service_worker/service_worker_context_client.h
diff --git a/content/renderer/service_worker/service_worker_context_client.h b/content/renderer/service_worker/service_worker_context_client.h
index 69b40659212fe22b726704830811707646749bb7..b32cab249ef82661f5bbae55ea08c71e5735b6b6 100644
--- a/content/renderer/service_worker/service_worker_context_client.h
+++ b/content/renderer/service_worker/service_worker_context_client.h
@@ -170,6 +170,9 @@ class ServiceWorkerContextClient : public blink::WebServiceWorkerContextClient,
   void didHandleSyncEvent(int request_id,
                           blink::WebServiceWorkerEventResult result,
                           double dispatch_event_time) override;
+  void didHandlePaymentRequestEvent(int request_id,
+                                    blink::WebServiceWorkerEventResult result,
+                                    double dispatch_event_time) override;
 
   // Called on the main thread.
   blink::WebServiceWorkerNetworkProvider* createServiceWorkerNetworkProvider(