chrome: Cleanup class/struct forward declarations

chrome/browser/chromeos/login/screens/update_model.h

 // Copyright 2015 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_CHROMEOS_LOGIN_SCREENS_UPDATE_MODEL_H_
 #define CHROME_BROWSER_CHROMEOS_LOGIN_SCREENS_UPDATE_MODEL_H_
 
 #include "chrome/browser/chromeos/login/screens/base_screen.h"
 
-namespace base {
-class ListValue;
-}
-
 namespace chromeos {
 
 class BaseScreenDelegate;
 class UpdateView;
 
 class UpdateModel : public BaseScreen {
  public:
   static const char kUserActionCancelUpdateShortcut[];
   static const char kContextKeyEstimatedTimeLeftSec[];
   static const char kContextKeyShowEstimatedTimeLeft[];
@@ skipping 11 matching lines @@
   std::string GetName() const override;
 
   // This method is called, when view is being destroyed. Note, if model
   // is destroyed earlier then it has to call Unbind().
   virtual void OnViewDestroyed(UpdateView* view) = 0;
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_LOGIN_SCREENS_UPDATE_MODEL_H_