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

cc/input/input_handler.h

 // Copyright 2011 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_INPUT_HANDLER_H_
 #define CC_INPUT_INPUT_HANDLER_H_
 
 #include <memory>
 
 #include "base/macros.h"
@@ skipping 114 matching lines @@
                                        ScrollInputType type) = 0;
 
   // Returns SCROLL_ON_IMPL_THREAD if a layer is actively being scrolled or
   // a subsequent call to ScrollAnimated can begin on the impl thread.
   virtual ScrollStatus ScrollAnimatedBegin(
       const gfx::Point& viewport_point) = 0;
 
   virtual ScrollStatus ScrollAnimated(const gfx::Point& viewport_point,
                                       const gfx::Vector2dF& scroll_delta) = 0;
 
+  virtual void AdjustDuration(base::TimeDelta) = 0;

[skobes, 2016/06/08 22:47:28]

I don't think we should ever adjust the duration after the fact. We should just
set it correctly in the first place.

+
   // Scroll the layer selected by |ScrollBegin| by given |scroll_state| delta.
   // Internally, the delta is transformed to local layer's coordinate space for
   // scrolls gestures that are direct manipulation (e.g. touch). If there is no
   // room to move the layer in the requested direction, its first ancestor layer
   // that can be scrolled will be moved instead. The return value's |did_scroll|
   // field is set to false if no layer can be moved in the requested direction
   // at all, and set to true if any layer is moved. If the scroll delta hits the
   // root layer, and the layer can no longer move, the root overscroll
   // accumulated within this ScrollBegin() scope is reported in the return
   // value's |accumulated_overscroll| field. Should only be called if
@@ skipping 58 matching lines @@
   InputHandler() {}
   virtual ~InputHandler() {}
 
  private:
   DISALLOW_COPY_AND_ASSIGN(InputHandler);
 };
 
 }  // namespace cc
 
 #endif  // CC_INPUT_INPUT_HANDLER_H_