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

third_party/WebKit/Source/core/paint/PaintLayerScrollableArea.h

 /*
  * Copyright (C) 2003, 2009, 2012 Apple Inc. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
  *   Randall Jesup <rjesup@wgate.com>
@@ skipping 463 matching lines @@
     m_hadVerticalScrollbarBeforeRelayout = val;
   }
 
   StickyConstraintsMap& stickyConstraintsMap() {
     return ensureRareData().m_stickyConstraintsMap;
   }
   void invalidateAllStickyConstraints();
   void invalidateStickyConstraintsFor(PaintLayer*,
                                       bool needsCompositingUpdate = true);
 
-  void removeStyleRelatedMainThreadScrollingReasons();
-  void addStyleRelatedMainThreadScrollingReasons(const uint32_t);
-  bool hasMainThreadScrollingReason(uint32_t reason) const {
-    return m_reasons & reason;
-  }
+  void resetStyleRelatedMainThreadScrollingReasons() { m_reasons = 0; }

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

reset only gets called from inside PLSA. Remove this method and just replace
with m_reasons = 0. Also, rename m_reasons to m_mainThreadScrollingReasons

[yigu, 2017/03/27 21:02:08]

Done.

+  uint32_t getStyleRelatedMainThreadScrollingReasons() { return m_reasons; }
 
   uint64_t id() const;
 
   DECLARE_VIRTUAL_TRACE();
 
  private:
   explicit PaintLayerScrollableArea(PaintLayer&);
 
   bool hasHorizontalOverflow() const;
   bool hasVerticalOverflow() const;
@@ skipping 105 matching lines @@
 
 DEFINE_TYPE_CASTS(PaintLayerScrollableArea,
                   ScrollableArea,
                   scrollableArea,
                   scrollableArea->isPaintLayerScrollableArea(),
                   scrollableArea.isPaintLayerScrollableArea());
 
 }  // namespace blink
 
 #endif  // LayerScrollableArea_h