Allow Blink to respond asynchronously to SW Push events (side 2/3)

public/web/WebServiceWorkerContextClient.h

Index: public/web/WebServiceWorkerContextClient.h
diff --git a/public/web/WebServiceWorkerContextClient.h b/public/web/WebServiceWorkerContextClient.h
index e7a8e1e4ee32ea6ba208d9f2b8ffa018dc27bba1..cfb7add05c7a726565b858d6852768bb1fd0a016 100644
--- a/public/web/WebServiceWorkerContextClient.h
+++ b/public/web/WebServiceWorkerContextClient.h
@@ -122,6 +122,11 @@ public:
     virtual void didHandleFetchEvent(int fetchEventID) { }
     virtual void didHandleFetchEvent(int fetchEventID, const WebServiceWorkerResponse& response) { }
 
+    // ServiceWorker specific method. Called after PushEvent (dispatched via
+    // WebServiceWorkerContextProxy) is handled by the ServiceWorker's script
+    // context.
+    virtual void didHandlePushEvent(int pushEventID, WebServiceWorkerEventResult result) { }
+
     // ServiceWorker specific method. Called after SyncEvent (dispatched via
     // WebServiceWorkerContextProxy) is handled by the ServiceWorker's script
     // context.