cros: Do not cache |root_window| in ScreenRotationAnimator.

ash/rotator/screen_rotation_animator.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 ASH_ROTATOR_SCREEN_ROTATION_ANIMATOR_H_
 #define ASH_ROTATOR_SCREEN_ROTATION_ANIMATOR_H_
 
 #include <stdint.h>
 
 #include "ash/ash_export.h"
 #include "base/callback_forward.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "base/observer_list.h"
 #include "ui/display/display.h"
 
-namespace aura {
-class Window;
-}  // namesapce aura
-
 namespace cc {
 class CopyOutputRequest;
 class CopyOutputResult;
 }  // namespace cc
 
 namespace ui {
 class AnimationMetricsReporter;
-class Layer;
 class LayerOwner;
 class LayerTreeOwner;
 }  // namespace ui
 
 namespace ash {
 namespace test {
 class ScreenRotationAnimatorTestApi;
 }  // namespace test
 
 class ScreenRotationAnimatorObserver;
@@ skipping 131 matching lines @@
   std::unique_ptr<ui::AnimationMetricsReporter> metrics_reporter_;
   // Only set in unittest to disable animation timers.
   bool disable_animation_timers_for_test_;
   base::ObserverList<ScreenRotationAnimatorObserver>
       screen_rotation_animator_observers_;
   std::unique_ptr<ui::LayerTreeOwner> old_layer_tree_owner_;
   std::unique_ptr<ui::LayerTreeOwner> new_layer_tree_owner_;
   std::unique_ptr<ui::LayerOwner> black_mask_layer_owner_;
   std::unique_ptr<ScreenRotationRequest> last_pending_request_;
   bool has_switch_ash_disable_smooth_screen_rotation_;
-  aura::Window* root_window_;
-  ui::Layer* screen_rotation_container_layer_;
   base::WeakPtrFactory<ScreenRotationAnimator> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ScreenRotationAnimator);
 };
 
 }  // namespace ash
 
 #endif  // ASH_ROTATOR_SCREEN_ROTATION_ANIMATOR_H_