We have a problem in the process on destroying WebContentsImpl because

chrome/browser/extensions/script_executor.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/extensions/script_executor.h"
 
 #include "base/callback.h"
 #include "base/logging.h"
 #include "base/pickle.h"
 #include "content/public/browser/render_view_host.h"
@@ skipping 46 matching lines @@
     if (message_request_id != request_id_)
       return false;
 
     IPC_BEGIN_MESSAGE_MAP(Handler, message)
       IPC_MESSAGE_HANDLER(ExtensionHostMsg_ExecuteCodeFinished,
                           OnExecuteCodeFinished)
     IPC_END_MESSAGE_MAP()
     return true;
   }
 
-  virtual void WebContentsDestroyed(content::WebContents* tab) OVERRIDE {
+  virtual void WebContentsDestroyed() OVERRIDE {
     base::ListValue val;
     callback_.Run(kRendererDestroyed, -1, GURL(std::string()), val);
     delete this;
   }
 
  private:
   void OnExecuteCodeFinished(int request_id,
                              const std::string& error,
                              int32 on_page_id,
                              const GURL& on_url,
@@ skipping 54 matching lines @@
   params.webview_src = webview_src;
   params.file_url = file_url;
   params.wants_result = (result_type == JSON_SERIALIZED_RESULT);
   params.user_gesture = user_gesture;
 
   // Handler handles IPCs and deletes itself on completion.
   new Handler(script_observers_, web_contents_, params, callback);
 }
 
 }  // namespace extensions