Turn WorkerLoaderProxy into a threadsafe, ref-counted object.

Source/core/loader/WorkerThreadableLoader.h

 /*
  * Copyright (C) 2009 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 69 matching lines @@
         //
         // case 2. xhr gets aborted and the worker context continues running.
         //    The ThreadableLoaderClientWrapper has the underlying client cleared, so no more calls
         //    go through it.  All tasks posted from the worker object's thread to the worker context's
         //    thread do "ThreadableLoaderClientWrapper::ref" (automatically inside of the cross thread copy
         //    done in createCrossThreadTask), so the ThreadableLoaderClientWrapper instance is there until all
         //    tasks are executed.
         class MainThreadBridge final : public ThreadableLoaderClient {
         public:
             // All executed on the worker context's thread.
-            MainThreadBridge(PassRefPtr<ThreadableLoaderClientWrapper>, PassOwnPtr<ThreadableLoaderClient>, WorkerLoaderProxy&, const ResourceRequest&, const ThreadableLoaderOptions&, const ResourceLoaderOptions&, const String& outgoingReferrer);
+            MainThreadBridge(PassRefPtr<ThreadableLoaderClientWrapper>, PassOwnPtr<ThreadableLoaderClient>, PassRefPtr<WorkerLoaderProxy>, const ResourceRequest&, const ThreadableLoaderOptions&, const ResourceLoaderOptions&, const String& outgoingReferrer);
             void overrideTimeout(unsigned long timeoutMilliseconds);
             void cancel();
             void destroy();
 
         private:
             // Executed on the worker context's thread.
             void clearClientWrapper();
 
             // All executed on the main thread.
             static void mainThreadDestroy(ExecutionContext*, MainThreadBridge*);
@@ skipping 14 matching lines @@
 
             // Only to be used on the main thread.
             RefPtr<ThreadableLoader> m_mainThreadLoader;
             OwnPtr<ThreadableLoaderClient> m_clientBridge;
 
             // ThreadableLoaderClientWrapper is to be used on the worker context thread.
             // The ref counting is done on either thread.
             RefPtr<ThreadableLoaderClientWrapper> m_workerClientWrapper;
 
             // Used on the worker context thread.
-            WorkerLoaderProxy& m_loaderProxy;
+            RefPtr<WorkerLoaderProxy> m_loaderProxy;
         };
 
         WorkerThreadableLoader(WorkerGlobalScope&, PassRefPtr<ThreadableLoaderClientWrapper>, PassOwnPtr<ThreadableLoaderClient>, const ResourceRequest&, const ThreadableLoaderOptions&, const ResourceLoaderOptions&);
 
         RefPtrWillBePersistent<WorkerGlobalScope> m_workerGlobalScope;
         RefPtr<ThreadableLoaderClientWrapper> m_workerClientWrapper;
         MainThreadBridge& m_bridge;
     };
 
 } // namespace blink
 
 #endif // WorkerThreadableLoader_h