Update from https://crrev.com/318214

cc/input/top_controls_manager.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_INPUT_TOP_CONTROLS_MANAGER_H_
 #define CC_INPUT_TOP_CONTROLS_MANAGER_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "cc/input/top_controls_state.h"
@@ skipping 43 matching lines @@
 
   void ScrollBegin();
   gfx::Vector2dF ScrollBy(const gfx::Vector2dF& pending_delta);
   void ScrollEnd();
 
   // The caller should ensure that |Pinch{Begin,End}| are called within
   // the scope of |Scroll{Begin,End}|.
   void PinchBegin();
   void PinchEnd();
 
+  void MainThreadHasStoppedFlinging();
+
   gfx::Vector2dF Animate(base::TimeTicks monotonic_time);
 
  protected:
   TopControlsManager(TopControlsManagerClient* client,
                      float top_controls_show_threshold,
                      float top_controls_hide_threshold);
 
  private:
   void ResetAnimations();
   void SetupAnimation(AnimationDirection direction);
   void StartAnimationIfNecessary();
   bool IsAnimationCompleteAtTime(base::TimeTicks time);
+  void ResetBaseline();
 
   TopControlsManagerClient* client_;  // The client manages the lifecycle of
                                       // this.
 
   scoped_ptr<KeyframedFloatAnimationCurve> top_controls_animation_;
   AnimationDirection animation_direction_;
   TopControlsState permitted_state_;
 
-  float current_scroll_delta_;
-  float controls_scroll_begin_offset_;
+  // Accumulated scroll delta since last baseline reset
+  float accumulated_scroll_delta_;
+
+  // Content offset when last baseline reset occurred
+  float baseline_content_offset_;
 
   // The percent height of the visible top control such that it must be shown
   // when the user stops the scroll.
   float top_controls_show_threshold_;
 
   // The percent height of the visible top control such that it must be hidden
   // when the user stops the scroll.
   float top_controls_hide_threshold_;
 
   bool pinch_gesture_active_;
 
   DISALLOW_COPY_AND_ASSIGN(TopControlsManager);
 };
 
 }  // namespace cc
 
 #endif  // CC_INPUT_TOP_CONTROLS_MANAGER_H_