Take MT jank into account when animating the scroll offset on CC

cc/layers/viewport.cc

Index: cc/layers/viewport.cc
diff --git a/cc/layers/viewport.cc b/cc/layers/viewport.cc
index d80d40c9f2533f57f04651fe39829f282cede14a..5022e1aaa659bb2b3bc09291493e665e79af2e9e 100644
--- a/cc/layers/viewport.cc
+++ b/cc/layers/viewport.cc
@@ -73,7 +73,8 @@ bool Viewport::ShouldAnimateViewport(const gfx::Vector2dF& viewport_delta,
   return max_dim_viewport_delta > max_dim_pending_delta;
 }
 
-gfx::Vector2dF Viewport::ScrollAnimated(const gfx::Vector2dF& delta) {
+gfx::Vector2dF Viewport::ScrollAnimated(const gfx::Vector2dF& delta,
+                                        base::TimeTicks original_event_time) {
   ScrollTree& scroll_tree =
       host_impl_->active_tree()->property_trees()->scroll_tree;
 
@@ -104,10 +105,12 @@ gfx::Vector2dF Viewport::ScrollAnimated(const gfx::Vector2dF& delta) {
   bool will_animate = false;
   if (ShouldAnimateViewport(inner_delta, outer_delta)) {
     scroll_tree.ScrollBy(outer_node, outer_delta, host_impl_->active_tree());
-    will_animate = host_impl_->ScrollAnimationCreate(inner_node, inner_delta);
+    will_animate = host_impl_->ScrollAnimationCreate(inner_node, inner_delta,
+                                                     original_event_time);
   } else {
     scroll_tree.ScrollBy(inner_node, inner_delta, host_impl_->active_tree());
-    will_animate = host_impl_->ScrollAnimationCreate(outer_node, outer_delta);
+    will_animate = host_impl_->ScrollAnimationCreate(outer_node, outer_delta,
+                                                     original_event_time);
   }
 
   if (will_animate) {