cros: Do not cache |root_window| in ScreenRotationAnimator.

ash/rotator/screen_rotation_animator.h

Index: ash/rotator/screen_rotation_animator.h
diff --git a/ash/rotator/screen_rotation_animator.h b/ash/rotator/screen_rotation_animator.h
index 1c1a5c757c4e19c9263f9ca55480921bcc3762b8..550e92ebaff977a64036b40a84f9d42dea3a0e1f 100644
--- a/ash/rotator/screen_rotation_animator.h
+++ b/ash/rotator/screen_rotation_animator.h
@@ -14,10 +14,6 @@
 #include "base/observer_list.h"
 #include "ui/display/display.h"
 
-namespace aura {
-class Window;
-}  // namesapce aura
-
 namespace cc {
 class CopyOutputRequest;
 class CopyOutputResult;
@@ -25,7 +21,6 @@ class CopyOutputResult;
 
 namespace ui {
 class AnimationMetricsReporter;
-class Layer;
 class LayerOwner;
 class LayerTreeOwner;
 }  // namespace ui
@@ -177,8 +172,6 @@ class ASH_EXPORT ScreenRotationAnimator {
   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);