Turn WorkerLoaderProxy into a threadsafe, ref-counted object.

Source/core/loader/WorkerLoaderClientBridge.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 27 matching lines @@
 namespace blink {
 
 class ThreadableLoaderClientWrapper;
 class WorkerLoaderProxy;
 
 // This bridge is created and destroyed on the worker thread, but is
 // passed to and used on the main thread. Each did* method relays the given
 // data to the client wrapper on the worker context thread.
 class WorkerLoaderClientBridge : public ThreadableLoaderClient {
 public:
-    static PassOwnPtr<ThreadableLoaderClient> create(PassRefPtr<ThreadableLoaderClientWrapper>, WorkerLoaderProxy&);
+    static PassOwnPtr<ThreadableLoaderClient> create(PassRefPtr<ThreadableLoaderClientWrapper>, PassRefPtr<WorkerLoaderProxy>);
     virtual ~WorkerLoaderClientBridge();
 
     virtual void didSendData(unsigned long long bytesSent, unsigned long long totalBytesToBeSent) override;
     virtual void didReceiveResponse(unsigned long identifier, const ResourceResponse&, PassOwnPtr<WebDataConsumerHandle>) override;
     virtual void didReceiveData(const char*, unsigned dataLength) override;
     virtual void didDownloadData(int dataLength) override;
     virtual void didReceiveCachedMetadata(const char*, int dataLength) override;
     virtual void didFinishLoading(unsigned long identifier, double finishTime) override;
     virtual void didFail(const ResourceError&) override;
     virtual void didFailAccessControlCheck(const ResourceError&) override;
     virtual void didFailRedirectCheck() override;
 
 private:
-    WorkerLoaderClientBridge(PassRefPtr<ThreadableLoaderClientWrapper>, WorkerLoaderProxy&);
+    WorkerLoaderClientBridge(PassRefPtr<ThreadableLoaderClientWrapper>, PassRefPtr<WorkerLoaderProxy>);
 
     // Used on the worker context thread, while its refcounting is done on
     // either thread.
     RefPtr<ThreadableLoaderClientWrapper> m_workerClientWrapper;
 
-    WorkerLoaderProxy& m_loaderProxy;
+    RefPtr<WorkerLoaderProxy> m_loaderProxy;
 };
 
 } // namespace blink
 
 #endif // WorkerLoaderClientBridge_h