Move viewport scrolling logic into separate class

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 73ed039e582363026274a82024477ab30b26ad71..b4d3782f5b9262b9cccef648b5301330326dbd24 100644
--- a/cc/trees/layer_tree_host_impl.h
+++ b/cc/trees/layer_tree_host_impl.h
@@ -63,6 +63,7 @@ class TextureMailboxDeleter;
 class TopControlsManager;
 class UIResourceBitmap;
 class UIResourceRequest;
+class Viewport;
 struct RendererCapabilitiesImpl;
 
 enum class GpuRasterizationStatus {
@@ -522,6 +523,15 @@ class CC_EXPORT LayerTreeHostImpl
     return frame_timing_tracker_.get();
   }
 
+  gfx::Vector2dF ScrollLayerWithViewportSpaceDelta(
+      LayerImpl* layer_impl,
+      const gfx::PointF& viewport_point,
+      const gfx::Vector2dF& viewport_delta);
+  gfx::Vector2dF ScrollLayerWithLocalDelta(
+      LayerImpl* layer_impl,
+      const gfx::Vector2dF& local_delta,
+      float page_scale_factor) const;
+
  protected:
   LayerTreeHostImpl(
       const LayerTreeSettings& settings,
@@ -549,6 +559,8 @@ class CC_EXPORT LayerTreeHostImpl
 
   bool IsSynchronousSingleThreaded() const;
 
+  Viewport* Viewport();
+
   // Scroll by preferring to move the outer viewport first, only moving the
   // inner if the outer is at its scroll extents.
   void ScrollViewportBy(gfx::Vector2dF scroll_delta);
@@ -559,14 +571,6 @@ class CC_EXPORT LayerTreeHostImpl
   void AnimateScrollbars(base::TimeTicks monotonic_time);
   void AnimateTopControls(base::TimeTicks monotonic_time);
 
-  bool ShouldTopControlsConsumeScroll(const gfx::Vector2dF& scroll_delta) const;
-
-  gfx::Vector2dF ScrollLayerWithViewportSpaceDelta(
-      LayerImpl* layer_impl,
-      float scale_from_viewport_to_screen_space,
-      const gfx::PointF& viewport_point,
-      const gfx::Vector2dF& viewport_delta);
-
   void TrackDamageForAllSurfaces(
       LayerImpl* root_draw_layer,
       const LayerImplList& render_surface_layer_list);