We have a problem in the process on destroying WebContentsImpl because

chrome/browser/apps/ephemeral_app_launcher.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_APPS_EPHEMERAL_APP_LAUNCHER_H_
 #define CHROME_BROWSER_APPS_EPHEMERAL_APP_LAUNCHER_H_
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 72 matching lines @@
       std::string* error) const OVERRIDE;
   virtual bool CheckInstallValid(
       const base::DictionaryValue& manifest,
       std::string* error) OVERRIDE;
   virtual scoped_ptr<ExtensionInstallPrompt> CreateInstallUI() OVERRIDE;
   virtual scoped_ptr<extensions::WebstoreInstaller::Approval>
       CreateApproval() const OVERRIDE;
   virtual void CompleteInstall(const std::string& error) OVERRIDE;
 
   // content::WebContentsObserver implementation.
-  virtual void WebContentsDestroyed(
-      content::WebContents* web_contents) OVERRIDE;
+  virtual void WebContentsDestroyed() OVERRIDE;
 
   // ExtensionRegistryObserver implementation.
   virtual void OnExtensionLoaded(
       content::BrowserContext* browser_context,
       const extensions::Extension* extension) OVERRIDE;
 
   // ExtensionEnableFlowDelegate implementation.
   virtual void ExtensionEnableFlowFinished() OVERRIDE;
   virtual void ExtensionEnableFlowAborted(bool user_initiated) OVERRIDE;
 
   // Listen to extension unloaded notifications.
   ScopedObserver<extensions::ExtensionRegistry,
                  extensions::ExtensionRegistryObserver>
       extension_registry_observer_;
 
   gfx::NativeWindow parent_window_;
   scoped_ptr<content::WebContents> dummy_web_contents_;
 
   // Created in CheckInstallValid().
   scoped_refptr<extensions::Extension> extension_;
 
   scoped_ptr<ExtensionEnableFlow> extension_enable_flow_;
 
   DISALLOW_COPY_AND_ASSIGN(EphemeralAppLauncher);
 };
 
 #endif  // CHROME_BROWSER_APPS_EPHEMERAL_APP_LAUNCHER_H_