Revert of Move ThreadableLoader to Oilpan heap (2/3)

third_party/WebKit/Source/web/AssociatedURLLoader.h

 /*
  * Copyright (C) 2010, 2011 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 66 matching lines @@
         m_client = nullptr;
         return client;
     }
 
     WebURLLoaderClient* m_client;
     WebURLLoaderOptions m_options;
 
     // An adapter which converts the DocumentThreadableLoaderClient method
     // calls into the WebURLLoaderClient method calls.
     std::unique_ptr<ClientAdapter> m_clientAdapter;
-    Persistent<DocumentThreadableLoader> m_loader;
+    std::unique_ptr<DocumentThreadableLoader> m_loader;
 
     // A ContextLifecycleObserver for cancelling |m_loader| when the Document
     // is detached.
     Persistent<Observer> m_observer;
 };
 
 } // namespace blink
 
 #endif