Fix app_shell shutdown crash due to BrowserContextKeyedServices

apps/shell/shell_extensions_browser_client.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 APPS_SHELL_SHELL_EXTENSIONS_BROWSER_CLIENT_H_
 #define APPS_SHELL_SHELL_EXTENSIONS_BROWSER_CLIENT_H_
 
 #include "base/compiler_specific.h"
 #include "extensions/browser/extensions_browser_client.h"
 
@@ skipping 27 matching lines @@
       content::BrowserContext* context) OVERRIDE;
   virtual bool DeferLoadingBackgroundHosts(content::BrowserContext* context)
       const OVERRIDE;
   virtual bool IsBackgroundPageAllowed(content::BrowserContext* context)
       const OVERRIDE;
   virtual bool DidVersionUpdate(content::BrowserContext* context) OVERRIDE;
   virtual scoped_ptr<extensions::AppSorting> CreateAppSorting() OVERRIDE;
   virtual bool IsRunningInForcedAppMode() OVERRIDE;
   virtual content::JavaScriptDialogManager* GetJavaScriptDialogManager()
       OVERRIDE;
+  virtual std::vector<BrowserContextKeyedServiceFactory*>
+      GetExtensionSystemDependencies() OVERRIDE;
+  virtual extensions::ExtensionSystem* CreateExtensionSystem(
+      content::BrowserContext* context) OVERRIDE;
 
  private:
   // The single BrowserContext for app_shell. Not owned.
   content::BrowserContext* browser_context_;
 
   // The PrefService for |browser_context_|.
   scoped_ptr<PrefService> prefs_;
 
   DISALLOW_COPY_AND_ASSIGN(ShellExtensionsBrowserClient);
 };
 
 }  // namespace apps
 
 #endif  // APPS_SHELL_SHELL_EXTENSIONS_BROWSER_CLIENT_H_