Service Worker: Migrate to version_uuid and surface ServiceWorker.id. (Blink 1/3)

public/web/WebServiceWorkerNetworkProvider.h

 /*
  * Copyright (C) 2014 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 37 matching lines @@
     // is writable, and changes to the URL, for example, will change the request
     // made.
     virtual void willSendRequest(WebDataSource*, WebURLRequest&) { }
 
     // Whether the document associated with WebDataSource is controlled by the
     // ServiceWorker.
     virtual bool isControlledByServiceWorker(WebDataSource&) { return false; }
 
     // Returns an identifier of the service worker controlling the document
     // associated with the WebDataSource.
-    virtual int64_t serviceWorkerID(WebDataSource&) { return -1; }
+    virtual std::string serviceWorkerID(WebDataSource&) { return std::string(); }
 };
 
 } // namespace blink
 
 #endif // WebServiceWorkerNetworkProvider_h