Let ThreadableLoaderClientWrapper's client handle failures better.

Source/core/loader/ThreadableLoaderClientWrapper.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 79 matching lines @@
 
     void didFail(const ResourceError& error)
     {
         m_done = true;
         if (m_client)
             m_client->didFail(error);
     }
 
     void didFailAccessControlCheck(const ResourceError& error)
     {
-        m_done = true;
+        // Let the client first handle the failure by possibly issuing
+        // a didFail() with a cancellation error before marking this
+        // wrapper as 'done'.
         if (m_client)
             m_client->didFailAccessControlCheck(error);
+        m_done = true;

[abarth-chromium, 2014/06/22 14:48:26]

Is the client allowed to destroy |this| during the didFailAccessControlCheck
callback?

[sof, 2014/06/22 15:49:14]

I don't think it will be able to accomplish that per the "case 2" lifetime
comment next to the WorkerThreadableLoader::MainThreadBridge declaration, i.e.,
the ref count is upped across the call to the wrapper.

No implementation of this method (and didFailRedirectCheck()) will currently try
to delete the loader (and indirectly de-ref this wrapper object), but they
should be allowed to do so in general.

Does that make sense?

     }
 
     void didFailRedirectCheck()
     {
-        m_done = true;
         if (m_client)
             m_client->didFailRedirectCheck();
+        m_done = true;
     }
 
     void didReceiveAuthenticationCancellation(unsigned long identifier, const ResourceResponse& response)
     {
         if (m_client)
             m_client->didReceiveResponse(identifier, response);
     }
 
     void didDownloadData(int dataLength)
     {
         if (m_client)
             m_client->didDownloadData(dataLength);
     }
 
 protected:
     explicit ThreadableLoaderClientWrapper(ThreadableLoaderClient* client)
         : m_client(client)
         , m_done(false)
     {
     }
 
     ThreadableLoaderClient* m_client;
     bool m_done;
 };
 
 } // namespace WebCore
 
 #endif // ThreadableLoaderClientWrapper_h