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

cc/animation/scroll_offset_animations_impl.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/animation/scroll_offset_animations_impl.h"
 
 #include "cc/animation/animation_events.h"
 #include "cc/animation/animation_host.h"
 #include "cc/animation/animation_id_provider.h"
 #include "cc/animation/animation_player.h"
@@ skipping 74 matching lines @@
   new_target.SetToMax(gfx::ScrollOffset());
   new_target.SetToMin(max_scroll_offset);
 
   curve->UpdateTarget(
       animation->TrimTimeToCurrentIteration(frame_monotonic_time).InSecondsF(),
       new_target);
 
   return true;
 }
 
+void ScrollOffsetAnimationsImpl::ScrollAnimationAdjustDuration(
+    ElementId element_id,
+    base::TimeDelta adjustment) {
+  if (element_id != scroll_offset_animation_player_->element_id())
+    return;
+
+  if (!scroll_offset_animation_player_->element_animations())
+    return;
+
+  Animation* animation =
+      scroll_offset_animation_player_->element_animations()->GetAnimation(
+          TargetProperty::SCROLL_OFFSET);
+  if (!animation)
+    return;
+
+  ScrollOffsetAnimationCurve* curve =
+      animation->curve()->ToScrollOffsetAnimationCurve();
+  curve->AdjustDuration(adjustment);
+}
+
 void ScrollOffsetAnimationsImpl::ScrollAnimationApplyAdjustment(
     ElementId element_id,
     const gfx::Vector2dF& adjustment) {
   DCHECK(scroll_offset_animation_player_);
   if (element_id != scroll_offset_animation_player_->element_id())
     return;
 
   if (!scroll_offset_animation_player_->element_animations())
     return;
 
@@ skipping 42 matching lines @@
     ElementId element_id) {
   if (scroll_offset_animation_player_->element_id() != element_id) {
     if (scroll_offset_animation_player_->element_id())
       scroll_offset_animation_player_->DetachElement();
     if (element_id)
       scroll_offset_animation_player_->AttachElement(element_id);
   }
 }
 
 }  // namespace cc