BackgroundSync sync events need to be ExtendableEvents, blink side

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 116 matching lines @@
     virtual void didHandleNotificationClickEvent(int eventID, WebServiceWorkerEventResult result) { }
 
     // 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.
-    virtual void didHandleSyncEvent(int syncEventID) { }
+    // TODO(chasej): crbug.com/486890 - Remove after cleanup on content side
+    virtual void didHandleSyncEventDeprecated(int syncEventID) { }
+    virtual void didHandleSyncEvent(int syncEventID, WebServiceWorkerEventResult result) { }
 
     // ServiceWorker specific method. Called after CrossOriginConnectEvent
     // (dispatched via WebServiceWorkerContextProxy) is handled by the
     // ServiceWorker's script context.
     virtual void didHandleCrossOriginConnectEvent(int connectEventID, bool acceptConnect) { }
 
     // Ownership of the returned object is transferred to the caller.
     // This is called on the main thread.
     virtual WebServiceWorkerNetworkProvider* createServiceWorkerNetworkProvider(WebDataSource*) { return nullptr; }
 
@@ skipping 39 matching lines @@
     // should delete the callback after calling either onSuccess or onError.
     virtual void focus(const WebString& uuid, WebServiceWorkerClientCallbacks*) { BLINK_ASSERT_NOT_REACHED(); }
 
     // Ownership of the passed WebMessagePortChannel is NOT passed to the callee.
     virtual void stashMessagePort(WebMessagePortChannel*, const WebString& name) { BLINK_ASSERT_NOT_REACHED(); }
 };
 
 } // namespace blink
 
 #endif // WebServiceWorkerContextClient_h