Connect LTHI::ScrollAnimated to cc::Viewport

cc/trees/layer_tree_host_impl.h

Index: cc/trees/layer_tree_host_impl.h
diff --git a/cc/trees/layer_tree_host_impl.h b/cc/trees/layer_tree_host_impl.h
index a7d6b083235eca111337803d8af04cf9f367e3e1..9366c223c9bb82cf3d9824e1bd80a908ce1815ee 100644
--- a/cc/trees/layer_tree_host_impl.h
+++ b/cc/trees/layer_tree_host_impl.h
@@ -536,6 +536,11 @@ class CC_EXPORT LayerTreeHostImpl
     bool opaque;
   };
 
+  // Returns the amount of delta that can be applied to scroll_node, taking
+  // page scale into account.
+  gfx::Vector2dF ComputeScrollDelta(ScrollNode* scroll_node,
+                                    const gfx::Vector2dF& delta);
+
   void ScheduleMicroBenchmark(scoped_ptr<MicroBenchmarkImpl> benchmark);
 
   CompositorFrameMetadata MakeCompositorFrameMetadata() const;
@@ -616,6 +621,11 @@ class CC_EXPORT LayerTreeHostImpl
                                        const ScrollTree& scroll_tree,
                                        ScrollNode* scroll_node) const;
 
+  // Returns true if a scroll offset animation is created and false if we scroll
+  // by the desired amount without an animation.
+  bool ScrollAnimationCreate(ScrollNode* scroll_node,
+                             const gfx::Vector2dF& scroll_amount);
+
  protected:
   LayerTreeHostImpl(
       const LayerTreeSettings& settings,
@@ -714,9 +724,6 @@ class CC_EXPORT LayerTreeHostImpl
 
   void ScrollAnimationAbort(LayerImpl* layer_impl);
 
-  void ScrollAnimationCreate(ScrollNode* scroll_node,
-                             const gfx::ScrollOffset& target_offset,
-                             const gfx::ScrollOffset& current_offset);
   bool ScrollAnimationUpdateTarget(ScrollNode* scroll_node,
                                    const gfx::Vector2dF& scroll_delta);