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

cc/input/input_handler.h

Index: cc/input/input_handler.h
diff --git a/cc/input/input_handler.h b/cc/input/input_handler.h
index bd11a620bbff2038ab1a8e74a38abf5f56c39eee..8d0f0c49982fc87b4f3b8c784c3a3f98320eda78 100644
--- a/cc/input/input_handler.h
+++ b/cc/input/input_handler.h
@@ -128,8 +128,12 @@ class CC_EXPORT InputHandler {
   virtual ScrollStatus ScrollAnimatedBegin(
       const gfx::Point& viewport_point) = 0;
 
+  // Returns SCROLL_ON_IMPL_THREAD if an animation is initiated on the impl
+  // thread. delayed_by is the delay that is taken into account when determining
+  // the duration of the animation.
   virtual ScrollStatus ScrollAnimated(const gfx::Point& viewport_point,
-                                      const gfx::Vector2dF& scroll_delta) = 0;
+                                      const gfx::Vector2dF& scroll_delta,
+                                      base::TimeDelta delayed_by) = 0;
 
   // Scroll the layer selected by |ScrollBegin| by given |scroll_state| delta.
   // Internally, the delta is transformed to local layer's coordinate space for