CC Animations: Fix the case when main-thread player changes layer_id.

cc/animation/animation_player.cc

 // 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.
 
 #include "cc/animation/animation_player.h"
 
 #include "cc/animation/animation_delegate.h"
 #include "cc/animation/animation_host.h"
 #include "cc/animation/animation_timeline.h"
 #include "cc/animation/element_animations.h"
@@ skipping 136 matching lines @@
     auto animations_to_remove =
         std::remove_if(animations_.begin(), animations_.end(),
                        [animation_id](const scoped_ptr<Animation>& animation) {
                          return animation->id() == animation_id;
                        });
     animations_.erase(animations_to_remove, animations_.end());
   }
 }
 
 void AnimationPlayer::PushPropertiesTo(AnimationPlayer* player_impl) {
-  if (!element_animations_) {
-    if (player_impl->element_animations())
+  if (layer_id_ != player_impl->layer_id()) {
+    if (player_impl->layer_id())
       player_impl->DetachLayer();
-    return;
+    if (layer_id_)
+      player_impl->AttachLayer(layer_id_);
   }
-
-  DCHECK(layer_id_);
-  if (!player_impl->element_animations())
-    player_impl->AttachLayer(layer_id_);
 }
 
 void AnimationPlayer::NotifyAnimationStarted(
     base::TimeTicks monotonic_time,
     Animation::TargetProperty target_property,
     int group) {
   if (layer_animation_delegate_)
     layer_animation_delegate_->NotifyAnimationStarted(monotonic_time,
                                                       target_property, group);
 }
 
 void AnimationPlayer::NotifyAnimationFinished(
     base::TimeTicks monotonic_time,
     Animation::TargetProperty target_property,
     int group) {
   if (layer_animation_delegate_)
     layer_animation_delegate_->NotifyAnimationFinished(monotonic_time,
                                                        target_property, group);
 }
 
 void AnimationPlayer::SetNeedsCommit() {
   DCHECK(animation_host_);
   animation_host_->SetNeedsCommit();
   animation_host_->SetNeedsRebuildPropertyTrees();
 }
 
 }  // namespace cc