Move logic of recording main thread scrolling reasons from cc to blink::ScrollManager

third_party/WebKit/Source/core/input/ScrollManager.h

 // Copyright 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 ScrollManager_h
 #define ScrollManager_h
 
 #include "core/CoreExport.h"
 #include "core/page/EventWithHitTestResults.h"
 #include "platform/geometry/LayoutSize.h"
@@ skipping 73 matching lines @@
   bool canHandleGestureEvent(const GestureEventWithHitTestResults&);
 
   // These functions are related to |m_resizeScrollableArea|.
   bool inResizeMode() const;
   void resize(const WebMouseEvent&);
   // Clears |m_resizeScrollableArea|. if |shouldNotBeNull| is true this
   // function DCHECKs to make sure that variable is indeed not null.
   void clearResizeScrollableArea(bool shouldNotBeNull);
   void setResizeScrollableArea(PaintLayer*, IntPoint);
 
+  // Record main thread scrolling reasons. This should be no-op;

[bokan, 2017/03/24 17:55:54]

Why does this say it should be a no-op? Recording a histogram is an op :)

[yigu, 2017/03/27 21:02:07]

Done.

+  uint32_t computeMainThreadScrollingReasons(const Node&);
+  void recordMainThreadScrollingReasons(const uint32_t reasons,
+                                        const WebGestureDevice);
+
  private:
   WebInputEventResult handleGestureScrollUpdate(const WebGestureEvent&);
   WebInputEventResult handleGestureScrollBegin(const WebGestureEvent&);
 
   WebInputEventResult passScrollGestureEvent(const WebGestureEvent&,
                                              LayoutObject*);
 
   void clearGestureScrollState();
 
   void customizedScroll(const Node& startNode, ScrollState&);
@@ skipping 36 matching lines @@
 
   Member<PaintLayerScrollableArea> m_resizeScrollableArea;
 
   LayoutSize
       m_offsetFromResizeCorner;  // In the coords of m_resizeScrollableArea.
 };
 
 }  // namespace blink
 
 #endif  // ScrollManager_h