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

cc/animation/animation_host.h

Index: cc/animation/animation_host.h
diff --git a/cc/animation/animation_host.h b/cc/animation/animation_host.h
index ec6ceff5b03ff477d34e885635749bd3005b40d6..510486da0a56e6507b12fe2871a326140089e343 100644
--- a/cc/animation/animation_host.h
+++ b/cc/animation/animation_host.h
@@ -14,6 +14,10 @@
 #include "cc/animation/animation_events.h"
 #include "cc/base/cc_export.h"
 
+namespace gfx {
+class ScrollOffset;
+}
+
 namespace cc {
 
 class AnimationPlayer;
@@ -96,7 +100,18 @@ class CC_EXPORT AnimationHost {
   bool HasAnyAnimation(int layer_id) const;
   bool HasActiveAnimation(int layer_id) const;
 
+  void ImplOnlyScrollAnimationCreate(int layer_id,
+                                     const gfx::ScrollOffset& target_offset,
+                                     const gfx::ScrollOffset& current_offset);
+  bool ImplOnlyScrollAnimationUpdateTarget(
+      int layer_id,
+      const gfx::Vector2dF& scroll_delta,
+      const gfx::ScrollOffset& max_scroll_offset,
+      base::TimeTicks frame_monotonic_time);
+
  private:
+  class ScrollOffsetAnimations;
+
   // TODO(loyso): Temporary 1:1 mapping. AnimationPlayers share
   // LayerAnimationController for a given layer at the moment.
   // Introduce LayersAnimations for the many AnimationPlayers to many Layers
@@ -117,6 +132,8 @@ class CC_EXPORT AnimationHost {
   scoped_ptr<AnimationRegistrar> animation_registrar_;
   LayerTreeMutatorsClient* layer_tree_mutators_client_;
 
+  scoped_ptr<ScrollOffsetAnimations> scroll_offset_animations_;
+
   const bool is_impl_instance_;
 
   DISALLOW_COPY_AND_ASSIGN(AnimationHost);