We have a problem in the process on destroying WebContentsImpl because

components/web_modal/web_contents_modal_dialog_manager.h

 // Copyright 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.
 
 #ifndef COMPONENTS_WEB_MODAL_WEB_CONTENTS_MODAL_DIALOG_MANAGER_H_
 #define COMPONENTS_WEB_MODAL_WEB_CONTENTS_MODAL_DIALOG_MANAGER_H_
 
 #include <deque>
 
 #include "base/memory/scoped_ptr.h"
@@ skipping 92 matching lines @@
   // Closes all WebContentsModalDialogs.
   void CloseAllDialogs();
 
   // Overridden from content::WebContentsObserver:
   virtual void DidNavigateMainFrame(
       const content::LoadCommittedDetails& details,
       const content::FrameNavigateParams& params) OVERRIDE;
   virtual void DidGetIgnoredUIEvent() OVERRIDE;
   virtual void WasShown() OVERRIDE;
   virtual void WasHidden() OVERRIDE;
-  virtual void WebContentsDestroyed(content::WebContents* tab) OVERRIDE;
+  virtual void WebContentsDestroyed() OVERRIDE;
   virtual void DidAttachInterstitialPage() OVERRIDE;
 
   // Delegate for notifying our owner about stuff. Not owned by us.
   WebContentsModalDialogManagerDelegate* delegate_;
 
   // All active dialogs.
   WebContentsModalDialogList child_dialogs_;
 
   // True while closing the dialogs on WebContents close.
   bool closing_all_dialogs_;
 
   DISALLOW_COPY_AND_ASSIGN(WebContentsModalDialogManager);
 };
 
 }  // namespace web_modal
 
 #endif  // COMPONENTS_WEB_MODAL_WEB_CONTENTS_MODAL_DIALOG_MANAGER_H_