Include auto vertical scrollbar in intrinsicScrollbarLogicalWidth.

third_party/WebKit/Source/core/layout/LayoutBox.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2005 Allan Sandfeld Jensen (kde@carewolf.com)
  *           (C) 2005, 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Adobe Systems Incorporated. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 775 matching lines @@
     return getScrollableArea()->horizontalScrollbarHeight();
 }
 
 int LayoutBox::intrinsicScrollbarLogicalWidth() const
 {
     if (!hasOverflowClip())
         return 0;
 
     ASSERT(getScrollableArea());
 
-    if (isHorizontalWritingMode() && style()->overflowY() == OverflowScroll) {
+    if (isHorizontalWritingMode() && (style()->overflowY() == OverflowScroll || style()->overflowY() == OverflowAuto)) {

[skobes, 2016/05/16 20:55:53]

I will echo cbiesinger's question on the other thread :)

Can we kill this and just use scrollbarLogicalWidth?

         // Even with OverflowScroll, the scrollbar may not exist (crbug.com/415031).
         return getScrollableArea()->hasVerticalScrollbar() ? verticalScrollbarWidth() : 0;
     }
 
-    if (!isHorizontalWritingMode() && style()->overflowX() == OverflowScroll) {
+    if (!isHorizontalWritingMode() && (style()->overflowX() == OverflowScroll || style()->overflowX() == OverflowAuto)) {
         // Even with OverflowScroll, the scrollbar may not exist (crbug.com/415031).
         return getScrollableArea()->hasHorizontalScrollbar() ? horizontalScrollbarHeight() : 0;
     }
 
     return 0;
 }
 
 ScrollResult LayoutBox::scroll(ScrollGranularity granularity, const FloatSize& delta)
 {
     // Presumably the same issue as in setScrollTop. See crbug.com/343132.
@@ skipping 4139 matching lines @@
         m_rareData->m_snapAreas->remove(&snapArea);
     }
 }
 
 SnapAreaSet* LayoutBox::snapAreas() const
 {
     return m_rareData ? m_rareData->m_snapAreas.get() : nullptr;
 }
 
 } // namespace blink