Hit test on the layer tree rather than the RSLL

cc/trees/layer_tree_host_impl.cc

Index: cc/trees/layer_tree_host_impl.cc
diff --git a/cc/trees/layer_tree_host_impl.cc b/cc/trees/layer_tree_host_impl.cc
index 22aa83f96e64475358e493e1d47af6b193513b28..f08457520b28411087f33825104bc3746d10672d 100644
--- a/cc/trees/layer_tree_host_impl.cc
+++ b/cc/trees/layer_tree_host_impl.cc
@@ -490,8 +490,7 @@ bool LayerTreeHostImpl::HaveTouchEventHandlersAt(
 
   LayerImpl* layer_impl =
       LayerTreeHostCommon::FindLayerThatIsHitByPointInTouchHandlerRegion(
-          device_viewport_point,
-          active_tree_->RenderSurfaceLayerList());
+          device_viewport_point, active_tree_->root_layer());
   return layer_impl != NULL;
 }
 
@@ -2198,13 +2197,12 @@ InputHandler::ScrollStatus LayerTreeHostImpl::ScrollBegin(
   gfx::PointF device_viewport_point = gfx::ScalePoint(viewport_point,
                                                       device_scale_factor_);
   LayerImpl* layer_impl = LayerTreeHostCommon::FindLayerThatIsHitByPoint(
-      device_viewport_point,
-      active_tree_->RenderSurfaceLayerList());
+      device_viewport_point, active_tree_->root_layer());
 
   if (layer_impl) {
     LayerImpl* scroll_layer_impl =
         LayerTreeHostCommon::FindFirstScrollingLayerThatIsHitByPoint(
-            device_viewport_point, active_tree_->RenderSurfaceLayerList());
+            device_viewport_point, active_tree_->root_layer());
     if (scroll_layer_impl && !HasScrollAncestor(layer_impl, scroll_layer_impl))
       return ScrollUnknown;
   }
@@ -2573,8 +2571,7 @@ void LayerTreeHostImpl::MouseMoveAt(const gfx::Point& viewport_point) {
                                                       device_scale_factor_);
 
   LayerImpl* layer_impl = LayerTreeHostCommon::FindLayerThatIsHitByPoint(
-      device_viewport_point,
-      active_tree_->RenderSurfaceLayerList());
+      device_viewport_point, active_tree_->root_layer());
   if (HandleMouseOverScrollbar(layer_impl, device_viewport_point))
     return;