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

cc/animation/scroll_offset_animations_impl.h

 // Copyright (c) 2016 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.
 
 #ifndef CC_ANIMATION_SCROLL_OFFSET_ANIMATIONS_IMPL_H_
 #define CC_ANIMATION_SCROLL_OFFSET_ANIMATIONS_IMPL_H_
 
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
 #include "base/memory/ref_counted.h"
@@ skipping 22 matching lines @@
 
   void ScrollAnimationCreate(ElementId element_id,
                              const gfx::ScrollOffset& target_offset,
                              const gfx::ScrollOffset& current_offset);
 
   bool ScrollAnimationUpdateTarget(ElementId element_id,
                                    const gfx::Vector2dF& scroll_delta,
                                    const gfx::ScrollOffset& max_scroll_offset,
                                    base::TimeTicks frame_monotonic_time);
 
+  void ScrollAnimationAdjustDuration(ElementId element_id,
+                                     base::TimeDelta adjustment);
+
   // Aborts the currently running scroll offset animation on an element and
   // starts a new one offsetted by adjustment.
   void ScrollAnimationApplyAdjustment(ElementId element_id,
                                       const gfx::Vector2dF& adjustment);
 
   void ScrollAnimationAbort(bool needs_completion);
 
   // AnimationDelegate implementation.
   void NotifyAnimationStarted(base::TimeTicks monotonic_time,
                               TargetProperty::Type target_property,
@@ skipping 20 matching lines @@
   // I.e. only one element can have an impl-only scroll offset animation at
   // any given time.
   scoped_refptr<AnimationPlayer> scroll_offset_animation_player_;
 
   DISALLOW_COPY_AND_ASSIGN(ScrollOffsetAnimationsImpl);
 };
 
 }  // namespace cc
 
 #endif  // CC_ANIMATION_SCROLL_OFFSET_ANIMATIONS_IMPL_H_