UI Compositor: Fix threaded animation survival if layer removed and added.

ui/compositor/layer_animator.h

Index: ui/compositor/layer_animator.h
diff --git a/ui/compositor/layer_animator.h b/ui/compositor/layer_animator.h
index 349fd75b97565ec10ce0c1c35a447f81bb467f1d..48e8a1e0ab40c4a36ecebb8d70f790273b57f2ba 100644
--- a/ui/compositor/layer_animator.h
+++ b/ui/compositor/layer_animator.h
@@ -26,6 +26,7 @@ class Animation;
 class AnimationPlayer;
 class AnimationTimeline;
 class Layer;
+class LayerAnimationController;
 }
 
 namespace gfx {
@@ -391,6 +392,11 @@ class COMPOSITOR_EXPORT LayerAnimator
   // aborted.
   base::ObserverList<LayerAnimationObserver> observers_;
 
+  // We store a state of LayerAnimationController here to save it in
+  // ResetCompositor/SetCompositor scope.
+  // TODO(loyso): Remove it. crbug.com/592873.
+  scoped_refptr<cc::LayerAnimationController> animation_controller_state_;
+
   DISALLOW_COPY_AND_ASSIGN(LayerAnimator);
 };