Push API: define push event on Service Worker.

public/web/WebServiceWorkerContextProxy.h

Index: public/web/WebServiceWorkerContextProxy.h
diff --git a/public/web/WebServiceWorkerContextProxy.h b/public/web/WebServiceWorkerContextProxy.h
index 7c1c4e341e43635e43978cd56150d67944d7339b..6c6328d0bff08558f93467121aed29e30a8854f9 100644
--- a/public/web/WebServiceWorkerContextProxy.h
+++ b/public/web/WebServiceWorkerContextProxy.h
@@ -51,6 +51,8 @@ public:
 
     virtual void dispatchMessageEvent(const WebString& message, const WebMessagePortChannelArray& channels) = 0;
 
+    virtual void dispatchPushEvent(int eventID, const WebString& data) = 0;
+
     // Once the ServiceWorker has finished handling the sync event
     // didHandleSyncEvent is called on the context client.
     virtual void dispatchSyncEvent(int syncEventID) = 0;