Handle new screen rotation request while waiting for the copy request callback.

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"
@@ skipping 46 matching lines @@
 
   // When screen rotation animation is ended or aborted, calls |Rotate()| with
   // the pending rotation request if the request queue is not empty. Otherwise
   // notifies |screen_rotation_animator_observer_|.
   void ProcessAnimationQueue();
 
  protected:
   using CopyCallback =
       base::Callback<void(std::unique_ptr<cc::CopyOutputResult> result)>;
   struct ScreenRotationRequest {
-    ScreenRotationRequest(display::Display::Rotation to_rotation,
+    ScreenRotationRequest(int64_t id,
+                          display::Display::Rotation to_rotation,
                           display::Display::RotationSource from_source)
-        : new_rotation(to_rotation), source(from_source) {}
+        : id(id), new_rotation(to_rotation), source(from_source) {}
+    int64_t id;
     display::Display::Rotation new_rotation;
     display::Display::RotationSource source;
   };
 
   // This function can be overridden in unit test to test removing external
   // display.
   virtual CopyCallback CreateAfterCopyCallback(
       std::unique_ptr<ScreenRotationRequest> rotation_request);
 
  private:
@@ skipping 36 matching lines @@
   // For current slow rotation animation, there are two states |ROTATING| and
   // |IDLE|. For the smooth rotation animation, we need to send copy request
   // and get copy result before animating.
   enum ScreenRotationState {
     COPY_REQUESTED,
     ROTATING,
     IDLE,
   };
   ScreenRotationState screen_rotation_state_;
 
+  // Rotation request id, used to ignore copy request callback if we decide to
+  // cancel the previous rotation request.
+  int64_t rotation_request_id_;

[oshima, 2017/04/13 18:18:24]

= 0

[wutao, 2017/04/13 18:54:30]

Keep as it. I init it in the init list.

+
   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<ScreenRotationRequest> last_pending_request_;
   base::WeakPtrFactory<ScreenRotationAnimator> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ScreenRotationAnimator);
 };
 
 }  // namespace ash
 
 #endif  // ASH_ROTATOR_SCREEN_ROTATION_ANIMATOR_H_