Revert of Pinch/Zoom Infrastructure & Plumbing CL

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 5b429f631002f063997b67dc829e3be86d938fa4..2b85e321c33940f88a560c34e23403035e36d59d 100644
--- a/cc/trees/layer_tree_host_impl.h
+++ b/cc/trees/layer_tree_host_impl.h
@@ -277,8 +277,7 @@
 
   // Shortcuts to layers on the active tree.
   LayerImpl* RootLayer() const;
-  LayerImpl* InnerViewportScrollLayer() const;
-  LayerImpl* OuterViewportScrollLayer() const;
+  LayerImpl* RootScrollLayer() const;
   LayerImpl* CurrentlyScrollingLayer() const;
 
   int scroll_layer_id_when_mouse_over_scrollbar() {
@@ -465,7 +464,6 @@
   void ReleaseTreeResources();
   void EnforceZeroBudget(bool zero_budget);
 
-  void ScrollViewportBy(gfx::Vector2dF scroll_delta);
   void AnimatePageScale(base::TimeTicks monotonic_time);
   void AnimateScrollbars(base::TimeTicks monotonic_time);
   void AnimateTopControls(base::TimeTicks monotonic_time);
@@ -476,6 +474,7 @@
       const gfx::PointF& viewport_point,
       const gfx::Vector2dF& viewport_delta);
 
+  void UpdateMaxScrollOffset();
   void TrackDamageForAllSurfaces(
       LayerImpl* root_draw_layer,
       const LayerImplList& render_surface_layer_list);