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

cc/animation/scroll_offset_animation_curve.h

 // 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.
 
 #ifndef CC_ANIMATION_SCROLL_OFFSET_ANIMATION_CURVE_H_
 #define CC_ANIMATION_SCROLL_OFFSET_ANIMATION_CURVE_H_
 
 #include <memory>
 
 #include "base/macros.h"
 #include "base/time/time.h"
 #include "cc/animation/animation_curve.h"
 #include "cc/base/cc_export.h"
 #include "ui/gfx/geometry/scroll_offset.h"
 
 namespace cc {
 
 class TimingFunction;
 
 class CC_EXPORT ScrollOffsetAnimationCurve : public AnimationCurve {
  public:
   enum class DurationBehavior { DELTA_BASED, CONSTANT, INVERSE_DELTA };
   static std::unique_ptr<ScrollOffsetAnimationCurve> Create(
       const gfx::ScrollOffset& target_value,
       std::unique_ptr<TimingFunction> timing_function,
       DurationBehavior = DurationBehavior::DELTA_BASED);
 
+  static base::TimeDelta SegmentDuration(const gfx::Vector2dF& delta,
+                                         DurationBehavior behavior,
+                                         base::TimeDelta delayed_by);
+
   ~ScrollOffsetAnimationCurve() override;
 
-  void SetInitialValue(const gfx::ScrollOffset& initial_value);
+  void SetInitialValue(const gfx::ScrollOffset& initial_value,
+                       base::TimeDelta delayed_by = base::TimeDelta());
   bool HasSetInitialValue() const;
   gfx::ScrollOffset GetValue(base::TimeDelta t) const;
   gfx::ScrollOffset target_value() const { return target_value_; }
   void UpdateTarget(double t, const gfx::ScrollOffset& new_target);
   void ApplyAdjustment(const gfx::Vector2dF& adjustment);
 
   // AnimationCurve implementation
   base::TimeDelta Duration() const override;
   CurveType Type() const override;
   std::unique_ptr<AnimationCurve> Clone() const override;
@@ skipping 16 matching lines @@
   DurationBehavior duration_behavior_;
 
   bool has_set_initial_value_;
 
   DISALLOW_COPY_AND_ASSIGN(ScrollOffsetAnimationCurve);
 };
 
 }  // namespace cc
 
 #endif  // CC_ANIMATION_SCROLL_OFFSET_ANIMATION_CURVE_H_