Refactor Scroll Customization to share cc::ScrollStateData with blink.

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 7eaa142fde40031ce88e0237ff1b3724ced2ecbf..a9c7e52587abfbf3fc0a21f555abf2c6beecc2ec 100644
--- a/cc/trees/layer_tree_host_impl.cc
+++ b/cc/trees/layer_tree_host_impl.cc
@@ -2634,8 +2634,12 @@ InputHandler::ScrollStatus LayerTreeHostImpl::ScrollAnimated(
     return scroll_status;
   }
 
-  ScrollState scroll_state(0, 0, viewport_point.x(), viewport_point.y(), 0, 0,
-                           false, true, false);
+  ScrollStateData scroll_state_data;
+  scroll_state_data.start_position_x = viewport_point.x();
+  scroll_state_data.start_position_y = viewport_point.y();
+  scroll_state_data.is_in_inertial_phase = true;
+  ScrollState scroll_state(scroll_state_data);
+
   // ScrollAnimated is used for animated wheel scrolls. We find the first layer
   // that can scroll and set up an animation of its scroll offset. Note that
   // this does not currently go through the scroll customization and viewport
@@ -3854,7 +3858,8 @@ void LayerTreeHostImpl::LayerTransformIsPotentiallyAnimatingChanged(
 
 void LayerTreeHostImpl::ScrollOffsetAnimationFinished() {
   // TODO(majidvp): We should pass in the original starting scroll position here
-  ScrollState scroll_state(0, 0, 0, 0, 0, 0, false, false, false);
+  ScrollStateData scroll_state_data;
+  ScrollState scroll_state(scroll_state_data);
   ScrollEnd(&scroll_state);
 }