Fully (?) fix overflow: auto with delayed scroll updates

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 235 matching lines @@
     void scrollToYOffset(double y, ScrollOffsetClamping clamp = ScrollOffsetUnclamped, ScrollBehavior scrollBehavior = ScrollBehaviorInstant)
     {
         scrollToOffset(DoubleSize(scrollXOffset(), y), clamp, scrollBehavior);
     }
 
     void setScrollPosition(const DoublePoint& position, ScrollType scrollType, ScrollBehavior scrollBehavior = ScrollBehaviorInstant) override
     {
         scrollToOffset(toDoubleSize(position), ScrollOffsetClamped, scrollBehavior, scrollType);
     }
 
-    void updateAfterLayout();
+    bool updateAfterLayout(SubtreeLayoutScope* = nullptr);

[skobes, 2016/02/25 22:09:31]

Can you add a comment here explaining the return value?

     void updateAfterStyleChange(const ComputedStyle*);
     void updateAfterOverflowRecalc();
 
     bool updateAfterCompositingChange() override;
 
     bool hasScrollbar() const { return hasHorizontalScrollbar() || hasVerticalScrollbar(); }
     bool hasOverflowControls() const { return hasScrollbar() || scrollCorner() || resizer(); }
 
     LayoutScrollbarPart* scrollCorner() const override { return m_scrollCorner; }
 
@@ skipping 158 matching lines @@
 #endif
 };
 
 DEFINE_TYPE_CASTS(PaintLayerScrollableArea, ScrollableArea, scrollableArea,
     scrollableArea->isPaintLayerScrollableArea(),
     scrollableArea.isPaintLayerScrollableArea());
 
 } // namespace blink
 
 #endif // LayerScrollableArea_h