Expose the notificationclick and notificationerror events on ServiceWorkerGlobalScope

public/web/WebServiceWorkerContextClient.h

Index: public/web/WebServiceWorkerContextClient.h
diff --git a/public/web/WebServiceWorkerContextClient.h b/public/web/WebServiceWorkerContextClient.h
index cfb7add05c7a726565b858d6852768bb1fd0a016..17194793b095eb6950742c09327572665a1dcfcb 100644
--- a/public/web/WebServiceWorkerContextClient.h
+++ b/public/web/WebServiceWorkerContextClient.h
@@ -127,6 +127,12 @@ public:
     // context.
     virtual void didHandlePushEvent(int pushEventID, WebServiceWorkerEventResult result) { }
 
+    // ServiceWorker specific method. Called after NotificationClickEvent and
+    // NotificationErrorEvent (dispatched via WebServiceWorkerContextProxy) are
+    // handled by the ServiceWorker's script context.
+    virtual void didHandleNotificationClickEvent(int eventID, WebServiceWorkerEventResult result) { }
+    virtual void didHandleNotificationErrorEvent(int eventID, WebServiceWorkerEventResult result) { }
+
     // ServiceWorker specific method. Called after SyncEvent (dispatched via
     // WebServiceWorkerContextProxy) is handled by the ServiceWorker's script
     // context.