Dispatch the ServiceWorker "activate" event during activation

public/web/WebServiceWorkerContextClient.h

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 60 matching lines @@
     // This is called on the main thread.
     virtual void workerContextFailedToStart() { }
 
     // Called when the WorkerGlobalScope had an error or an exception.
     virtual void reportException(const WebString& errorMessage, int lineNumber, int columnNumber, const WebString& sourceURL) { }
 
     // Inspector related messages.
     virtual void dispatchDevToolsMessage(const WebString&) { }
     virtual void saveDevToolsAgentState(const WebString&) { }
 
+    // ServiceWorker specific method.
+    virtual void didHandleActivateEvent(int eventID, blink::WebServiceWorkerEventResult result) { }
+
     // ServiceWorker specific method. Called after InstallEvent (dispatched
     // via WebServiceWorkerContextProxy) is handled by the ServiceWorker's
     // script context.
     virtual void didHandleInstallEvent(int installEventID) { }
     virtual void didHandleInstallEvent(int installEventID, blink::WebServiceWorkerEventResult result)
     {
         didHandleInstallEvent(installEventID);
     }
 
     // ServiceWorker specific methods. Called after FetchEvent is handled by the
     // ServiceWorker's script context. When no response is provided, the browser
     // should fallback to native fetch.
     virtual void didHandleFetchEvent(int fetchEventID) { }
     virtual void didHandleFetchEvent(int fetchEventID, const WebServiceWorkerResponse& response) { }
 
     // Ownership of the returned object is transferred to the caller.
     virtual WebServiceWorkerNetworkProvider* createServiceWorkerNetworkProvider(blink::WebDataSource*) { return 0; }
 
     // ServiceWorker specific method. Called after SyncEvent (dispatched via
     // WebServiceWorkerContextProxy) is handled by the ServiceWorker's script
     // context.
     virtual void didHandleSyncEvent(int syncEventID) { }
 };
 
 } // namespace blink
 
 #endif // WebWorkerContextClient_h