The blink half of the new ServiceWorker 'sync' event.

public/web/WebServiceWorkerContextClient.h

Index: public/web/WebServiceWorkerContextClient.h
diff --git a/public/web/WebServiceWorkerContextClient.h b/public/web/WebServiceWorkerContextClient.h
index d0c87b41664bb2668748feb73ccfd059e84e5c05..9ddfb453911b11deb3bcb59f36a8445a6809ebe5 100644
--- a/public/web/WebServiceWorkerContextClient.h
+++ b/public/web/WebServiceWorkerContextClient.h
@@ -84,6 +84,11 @@ public:
     // should fallback to native fetch.
     virtual void didHandleFetchEvent(int fetchEventID) { }
     virtual void didHandleFetchEvent(int fetchEventID, const WebServiceWorkerResponse& response) { }
+
+    // ServiceWorker specific method. Called after SyncEvent (dispatched via
+    // WebServiceWorkerContextProxy) is handled by the ServiceWorker's script
+    // context.
+    virtual void didHandleSyncEvent(int syncEventID) { }
 };
 
 } // namespace blink