Simplify adding callbacks.

chrome/browser/ui/webui/chromeos/login/update_screen_handler.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_UI_WEBUI_CHROMEOS_LOGIN_UPDATE_SCREEN_HANDLER_H_
 #define CHROME_BROWSER_UI_WEBUI_CHROMEOS_LOGIN_UPDATE_SCREEN_HANDLER_H_
 
 #include "base/compiler_specific.h"
 #include "chrome/browser/chromeos/login/screens/update_screen_actor.h"
 #include "chrome/browser/ui/webui/chromeos/login/base_screen_handler.h"
@@ skipping 22 matching lines @@
   virtual void ShowProgressMessage(bool visible) OVERRIDE;
   virtual void SetProgressMessage(ProgressMessage message) OVERRIDE;
   virtual void ShowCurtain(bool visible) OVERRIDE;
 
   // WebUIMessageHandler implementation:
   virtual void RegisterMessages() OVERRIDE;
 
  private:
 #if !defined(OFFICIAL_BUILD)
   // Called when user presses Escape to cancel update.
-  void HandleUpdateCancel(const base::ListValue* args);
+  void HandleUpdateCancel();
 #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_