CC Animations: Port Impl-only-scrolling to use compositor animation timelines.

cc/animation/animation_player.cc

Index: cc/animation/animation_player.cc
diff --git a/cc/animation/animation_player.cc b/cc/animation/animation_player.cc
index 603ffa97e939d10368c37a6d7808cce02ececd20..e4febeb242ace4204442b8dbc2cf0c9f3ba41bf3 100644
--- a/cc/animation/animation_player.cc
+++ b/cc/animation/animation_player.cc
@@ -119,6 +119,10 @@ void AnimationPlayer::UnbindElementAnimations() {
 }
 
 void AnimationPlayer::AddAnimation(scoped_ptr<Animation> animation) {
+  DCHECK_IMPLIES(
+      animation->target_property() == Animation::SCROLL_OFFSET,
+      animation_host_ && animation_host_->SupportsScrollAnimations());
+
   if (element_animations_) {
     element_animations_->layer_animation_controller()->AddAnimation(
         animation.Pass());