[cros] check for updates in WebUI OOBE can be cancelled in dev builds.

chrome/browser/ui/webui/chromeos/login/update_screen_handler.h

 // Copyright (c) 2011 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_WEBUI_CHROMEOS_LOGIN_UPDATE_SCREEN_HANDLER_H_
 #define CHROME_BROWSER_UI_WEBUI_CHROMEOS_LOGIN_UPDATE_SCREEN_HANDLER_H_
 
 #include "chrome/browser/chromeos/login/update_screen_actor.h"
 #include "chrome/browser/ui/webui/chromeos/login/base_screen_handler.h"
 
 namespace chromeos {
 
 class UpdateScreenHandler : public UpdateScreenActor,
                             public BaseScreenHandler {
  public:
   UpdateScreenHandler();
   virtual ~UpdateScreenHandler();
 
   // BaseScreenHandler implementation:
   virtual void GetLocalizedStrings(base::DictionaryValue* localized_strings);
   virtual void Initialize();
 
   // UpdateScreenActor implementation:
+  virtual void SetDelegate(UpdateScreenActor::Delegate* screen) OVERRIDE;
   virtual void Show();
   virtual void Hide();
   virtual void PrepareToShow();
   virtual void ShowManualRebootInfo();
   virtual void SetProgress(int progress);
   virtual void ShowCurtain(bool enable);
   virtual void ShowPreparingUpdatesInfo(bool visible);
 
   // WebUIMessageHandler implementation:
   virtual void RegisterMessages();
 
  private:
+#if !defined(OFFICIAL_BUILD)
+  // Called when user presses Escape to cancel update.
+  void HandleUpdateCancel(const base::ListValue* args);
+#endif
+
+  UpdateScreenActor::Delegate* screen_;
 
   // Keeps whether screen should be shown right after initialization.
   bool show_on_init_;
 
   DISALLOW_COPY_AND_ASSIGN(UpdateScreenHandler);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_UI_WEBUI_CHROMEOS_LOGIN_UPDATE_SCREEN_HANDLER_H_