Add an Error class for ServiceWorkers

public/platform/WebServiceWorkerProvider.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 20 matching lines @@
 #ifndef WebServiceWorkerProvider_h
 #define WebServiceWorkerProvider_h
 
 #include "public/platform/WebCallbacks.h"
 
 namespace WebKit {
 
 class WebString;
 class WebURL;
 class WebServiceWorker;
+struct WebServiceWorkerError;
 
 class WebServiceWorkerProvider {
 public:
-    typedef WebCallbacks<WebServiceWorker, WebServiceWorker> WebServiceWorkerCallbacks;
+    // The WebServiceWorker and WebServiceWorkerError ownership are passed to the WebServiceWorkerCallbacks implementation.
+    typedef WebCallbacks<WebServiceWorker, WebServiceWorkerError> WebServiceWorkerCallbacks;
     virtual void registerServiceWorker(const WebURL& pattern, const WebURL& scriptUrl, WebServiceWorkerCallbacks*) { }
 
     virtual void unregisterServiceWorker(const WebURL& pattern, WebServiceWorkerCallbacks*) { }
     virtual ~WebServiceWorkerProvider() { }
 };
 
 } // namespace WebKit
 
 #endif