Introducing the WebServiceWorkerCacheStorage.

public/platform/WebCallbacks.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 23 matching lines @@
 namespace blink {
 
 template<typename S, typename T>
 class WebCallbacks {
 public:
     virtual ~WebCallbacks() { };
     virtual void onSuccess(S*) { };
     virtual void onError(T*) { };
 };
 
+template<typename T>
+class WebCallbacks<void, T> {
+public:
+    virtual ~WebCallbacks() { };
+    virtual void onSuccess() { };
+    virtual void onError(T*) { };
+};
+
 } // namespace blink
 
 #endif