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

cc/animation/animation_host.h

 // Copyright 2015 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_ANIMATION_HOST_H_
 #define CC_ANIMATION_ANIMATION_HOST_H_
 
 #include <memory>
 #include <unordered_map>
 
@@ skipping 125 matching lines @@
 
   void ImplOnlyScrollAnimationCreate(ElementId element_id,
                                      const gfx::ScrollOffset& target_offset,
                                      const gfx::ScrollOffset& current_offset);
   bool ImplOnlyScrollAnimationUpdateTarget(
       ElementId element_id,
       const gfx::Vector2dF& scroll_delta,
       const gfx::ScrollOffset& max_scroll_offset,
       base::TimeTicks frame_monotonic_time);
 
+  void ImplOnlyScrollAnimationAdjustDuration(ElementId element_id,
+                                             base::TimeDelta adjustment);
+
   void ScrollAnimationAbort(bool needs_completion);
 
   // This should only be called from the main thread.
   ScrollOffsetAnimations& scroll_offset_animations() const;
 
   // Registers the given element animations as active. An active element
   // animations is one that has a running animation that needs to be ticked.
   void DidActivateElementAnimations(ElementAnimations* element_animations);
 
   // Unregisters the given element animations. When this happens, the
@@ skipping 39 matching lines @@
 
   bool supports_scroll_animations_;
   bool animation_waiting_for_deletion_;
 
   DISALLOW_COPY_AND_ASSIGN(AnimationHost);
 };
 
 }  // namespace cc
 
 #endif  // CC_ANIMATION_ANIMATION_HOST_H_