We have a problem in the process on destroying WebContentsImpl because

chrome/browser/ui/passwords/manage_passwords_bubble_model.h

 // Copyright 2013 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_PASSWORDS_MANAGE_PASSWORDS_BUBBLE_MODEL_H_
 #define CHROME_BROWSER_UI_PASSWORDS_MANAGE_PASSWORDS_BUBBLE_MODEL_H_
 
 #include "chrome/browser/ui/passwords/manage_passwords_bubble.h"
 #include "components/autofill/core/common/password_form.h"
 #include "components/password_manager/core/browser/password_manager_metrics_util.h"
@@ skipping 71 matching lines @@
   // Gets the reason the bubble was dismissed.
   password_manager::metrics_util::UIDismissalReason dismissal_reason() const {
     return dismissal_reason_;
   }
 
   // State setter.
   void set_state(password_manager::ui::State state) { state_ = state; }
 #endif
 
  private:
-  // content::WebContentsObserver
-  virtual void WebContentsDestroyed(
-      content::WebContents* web_contents) OVERRIDE;
-
-  content::WebContents* web_contents_;
   password_manager::ui::State state_;
   base::string16 title_;
   autofill::PasswordForm pending_credentials_;
   autofill::PasswordFormMap best_matches_;
   base::string16 manage_link_;
 
   password_manager::metrics_util::UIDisplayDisposition display_disposition_;
   password_manager::metrics_util::UIDismissalReason dismissal_reason_;
 
   DISALLOW_COPY_AND_ASSIGN(ManagePasswordsBubbleModel);
 };
 
 #endif  // CHROME_BROWSER_UI_PASSWORDS_MANAGE_PASSWORDS_BUBBLE_MODEL_H_