cros: Do not cache |root_window| in ScreenRotationAnimator.

ash/display/display_configuration_controller.h

 // Copyright 2016 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_CONFIGURATION_CONTROLLER_H_
 #define ASH_DISPLAY_DISPLAY_CONFIGURATION_CONTROLLER_H_
 
 #include <memory>
 
 #include "ash/ash_export.h"
@@ skipping 59 matching lines @@
   class DisplayChangeLimiter;
 
   // Sets the timeout for the DisplayChangeLimiter if it exists. Call this
   // *before* starting any animations.
   void SetThrottleTimeout(int64_t throttle_ms);
   bool IsLimited();
   void SetDisplayLayoutImpl(std::unique_ptr<display::DisplayLayout> layout);
   void SetMirrorModeImpl(bool mirror);
   void SetPrimaryDisplayIdImpl(int64_t display_id);
 
-  // Returns the ScreenRotationAnimator associated with the |display_id|. If
-  // there is no existing ScreenRotationAnimator for |display_id|, it will make
-  // one and store the pair in the |rotation_animator_map_|.
+  // Returns the ScreenRotationAnimator associated with the |display_id|'s
+  // |root_window|. If there is no existing ScreenRotationAnimator for
+  // |root_window|, it will make one and store in the |root_window| property
+  // |kScreenRotationAnimatorKey|.
   ScreenRotationAnimator* GetScreenRotationAnimatorForDisplay(
       int64_t display_id);
 
   display::DisplayManager* display_manager_;         // weak ptr
   WindowTreeHostManager* window_tree_host_manager_;  // weak ptr
   std::unique_ptr<DisplayAnimator> display_animator_;
   std::unique_ptr<DisplayChangeLimiter> limiter_;
 
-  // Tracks |display_id| to ScreenRotationAnimator mappings. The
-  // |rotation_animator_map_| is populated on demand the first time a
-  // ScreenRotationAnimator is needed for a given |display_id|.
-  // On animation ended or aborted, the animator may be deleted if there is no
-  // more pending rotation request.
-  std::unordered_map<int64_t, std::unique_ptr<ScreenRotationAnimator>>
-      rotation_animator_map_;
-
   base::WeakPtrFactory<DisplayConfigurationController> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(DisplayConfigurationController);
 };
 
 }  // namespace ash
 
 #endif  // ASH_DISPLAY_DISPLAY_CONFIGURATION_CONTROLLER_H_