We have a problem in the process on destroying WebContentsImpl because

chrome/browser/download/download_request_limiter.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_DOWNLOAD_DOWNLOAD_REQUEST_LIMITER_H_
 #define CHROME_BROWSER_DOWNLOAD_DOWNLOAD_REQUEST_LIMITER_H_
 
 #include <map>
 #include <string>
 #include <vector>
@@ skipping 94 matching lines @@
     content::WebContents* web_contents() const {
       return content::WebContentsObserver::web_contents();
     }
 
     // content::WebContentsObserver overrides.
     virtual void AboutToNavigateRenderView(
         content::RenderViewHost* render_view_host) OVERRIDE;
     // Invoked when a user gesture occurs (mouse click, enter or space). This
     // may result in invoking Remove on DownloadRequestLimiter.
     virtual void DidGetUserGesture() OVERRIDE;
-    virtual void WebContentsDestroyed(
-        content::WebContents* web_contents) OVERRIDE;
+    virtual void WebContentsDestroyed() OVERRIDE;
 
     // Asks the user if they really want to allow the download.
     // See description above CanDownloadOnIOThread for details on lifetime of
     // callback.
     void PromptUserForDownload(
         const DownloadRequestLimiter::Callback& callback);
 
     // Invoked from DownloadRequestDialogDelegate. Notifies the delegates and
     // changes the status appropriately. Virtual for testing.
     virtual void Cancel();
@@ skipping 131 matching lines @@
   StateMap state_map_;
 
   // Weak ptr factory used when |CanDownload| asks the delegate asynchronously
   // about the download.
   base::WeakPtrFactory<DownloadRequestLimiter> factory_;
 
   DISALLOW_COPY_AND_ASSIGN(DownloadRequestLimiter);
 };
 
 #endif  // CHROME_BROWSER_DOWNLOAD_DOWNLOAD_REQUEST_LIMITER_H_