ash: Cleanup class/struct forward declarations

ash/display/display_animator_chromeos.h

 // Copyright 2014 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 ASH_DISPLAY_DISPLAY_ANIMATOR_CHROMEOS_H_
 #define ASH_DISPLAY_DISPLAY_ANIMATOR_CHROMEOS_H_
 
 #include <map>
 #include <memory>
 
 #include "ash/ash_export.h"
 #include "ash/display/display_animator.h"
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "base/timer/timer.h"
 #include "ui/display/chromeos/display_configurator.h"
 
 namespace aura {
-class RootWindow;
 class Window;
 }  // namespace aura
 
 namespace ui {
 class Layer;
 }  // namespace ui
 
 namespace ash {
 
 // DisplayAnimatorChromeOS provides the visual effects for
@@ skipping 27 matching lines @@
   std::map<aura::Window*, std::unique_ptr<ui::Layer>> hiding_layers_;
   std::unique_ptr<base::OneShotTimer> timer_;
   base::WeakPtrFactory<DisplayAnimatorChromeOS> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(DisplayAnimatorChromeOS);
 };
 
 }  // namespace ash
 
 #endif  // ASH_DISPLAY_DISPLAY_ANIMATOR_CHROMEOS_H_