Add screen rotation animator lock.

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..584494c17afca51d1a466cddbd4ac3487803972b 100644
--- a/ash/rotator/screen_rotation_animator.h
+++ b/ash/rotator/screen_rotation_animator.h
@@ -35,6 +35,7 @@ namespace test {
 class ScreenRotationAnimatorTestApi;
 }  // namespace test
 
+class ScreenRotationAnimatorLock;
 class ScreenRotationAnimatorObserver;
 
 // Utility to perform a screen rotation with an animation.
@@ -66,6 +67,9 @@ class ASH_EXPORT ScreenRotationAnimator {
   // notifies |screen_rotation_animator_observer_|.
   void ProcessAnimationQueue();
 
+  void AddAnimatorLock(ScreenRotationAnimatorLock* lock);
+  void RemoveAnimatorLock(ScreenRotationAnimatorLock* lock);
+
  protected:
   using CopyCallback =
       base::Callback<void(std::unique_ptr<cc::CopyOutputResult> result)>;
@@ -150,6 +154,10 @@ class ASH_EXPORT ScreenRotationAnimator {
 
   void StopAnimating();
 
+  ScreenRotationAnimatorLock* CreateAnimatorLock();
+  void TimeoutAnimatorLocks();
+  void ResetCreatedAnimatorLocks();
+
   // The id of the display to rotate.
   int64_t display_id_;
 
@@ -167,6 +175,14 @@ class ASH_EXPORT ScreenRotationAnimator {
   // cancel the previous rotation request.
   int64_t rotation_request_id_;
 
+  // The cached rotation request while waiting for the animator lock.
+  std::unique_ptr<ScreenRotationRequest> rotation_request_after_unlock_;
+  // The active locks waiting for.
+  std::vector<ScreenRotationAnimatorLock*> active_locks_;
+  // All the unique_ptr of the locks created. Hold the ownership so that we can
+  // release after animation.
+  std::vector<std::unique_ptr<ScreenRotationAnimatorLock>> created_locks_;
+
   std::unique_ptr<ui::AnimationMetricsReporter> metrics_reporter_;
   // Only set in unittest to disable animation timers.
   bool disable_animation_timers_for_test_;
@@ -180,6 +196,7 @@ class ASH_EXPORT ScreenRotationAnimator {
   aura::Window* root_window_;
   ui::Layer* screen_rotation_container_layer_;
   base::WeakPtrFactory<ScreenRotationAnimator> weak_factory_;
+  base::WeakPtrFactory<ScreenRotationAnimator> lock_weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ScreenRotationAnimator);
 };