Uses copy request to flatten the layers to do screen rotation animation.

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/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "base/observer_list.h"
 #include "ui/display/display.h"
 
+namespace cc {
+class CopyOutputResult;
+}  // namespace cc
+
 namespace ui {
 class AnimationMetricsReporter;
 class Layer;
 class LayerTreeOwner;
 }  // namespace ui
 
 namespace ash {
 namespace test {
 class ScreenRotationAnimatorTestApi;
 }  // namespace test
@@ skipping 26 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();
 
  private:
   friend class ash::test::ScreenRotationAnimatorTestApi;
   struct ScreenRotationRequest;
 
-  // Set the screen orientation to |new_rotation| and animate the change. The
+  void StartRotationAnimation(
+      std::unique_ptr<ScreenRotationRequest> rotation_request);
+
+  // This is an asynchronous call to request copy output of root layer. In the
+  // callback, either succeeded or fail, it will call |AnimateRotation()|.
+  void RequestCopyRootLayerAndAnimateRotation(
+      std::unique_ptr<ScreenRotationRequest> rotation_request);
+
+  // The callback in |RequestCopyRootLayerAndAnimateRotation()|. No matter the
+  // request is succeeded or fail, it will call |AnimateRotation()|.
+  void OnRootLayerCopiedBeforeRotation(
+      std::unique_ptr<ScreenRotationRequest> rotation_request,
+      std::unique_ptr<cc::CopyOutputResult> result);
+
+  // Recreates all |root_window| layers.
+  void CreateOldLayerTree();
+
+  // Requests a copy of |root_window| root layer output.
+  void CopyOldLayerTree(std::unique_ptr<cc::CopyOutputResult> result);
+
+  // Note: Only call this function when the |old_layer_tree_owner_| is set up
+  // properly.
+  // Sets the screen orientation to |new_rotation| and animate the change. The
   // animation will rotate the initial orientation's layer towards the new
   // orientation through |rotation_degrees| while fading out, and the new
   // orientation's layer will be rotated in to the |new_orientation| through
   // |rotation_degrees| arc.
   void AnimateRotation(std::unique_ptr<ScreenRotationRequest> rotation_request);
 
   void set_disable_animation_timers_for_test(bool disable_timers);
 
   void StopAnimating();
 
   // The id of the display to rotate.
   int64_t display_id_;
   bool is_rotating_;
   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_