We have a problem in the process on destroying WebContentsImpl because

chrome/browser/ui/panels/panel_host.h

 // 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.
 
 #ifndef CHROME_BROWSER_UI_PANELS_PANEL_HOST_H_
 #define CHROME_BROWSER_UI_PANELS_PANEL_HOST_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "content/public/browser/web_contents_delegate.h"
@@ skipping 62 matching lines @@
       content::WebContents* source,
       const content::NativeWebKeyboardEvent& event) OVERRIDE;
   virtual void WebContentsFocused(content::WebContents* contents) OVERRIDE;
   virtual void ResizeDueToAutoResize(content::WebContents* web_contents,
                                      const gfx::Size& new_size) OVERRIDE;
 
   // content::WebContentsObserver overrides.
   virtual void RenderViewCreated(
       content::RenderViewHost* render_view_host) OVERRIDE;
   virtual void RenderProcessGone(base::TerminationStatus status) OVERRIDE;
-  virtual void WebContentsDestroyed(
-      content::WebContents* web_contents) OVERRIDE;
+  virtual void WebContentsDestroyed() OVERRIDE;
   virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
 
   // extensions::ExtensionFunctionDispatcher::Delegate overrides.
   virtual extensions::WindowController* GetExtensionWindowController() const
       OVERRIDE;
   virtual content::WebContents* GetAssociatedWebContents() const OVERRIDE;
 
   // Actions on web contents.
   void Reload();
   void ReloadIgnoringCache();
@@ skipping 13 matching lines @@
 
   scoped_ptr<content::WebContents> web_contents_;
 
   // The following factory is used to close the panel via the message loop.
   base::WeakPtrFactory<PanelHost> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(PanelHost);
 };
 
 #endif  // CHROME_BROWSER_UI_PANELS_PANEL_HOST_H_