[css-flexbox] Fix size comparison when scrollbars are present

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

 /*
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 503 matching lines @@
 LayoutUnit LayoutFlexibleBox::crossAxisIntrinsicExtentForChild(const LayoutBox& child) const
 {
     return hasOrthogonalFlow(child) ? childIntrinsicLogicalWidth(child) : childIntrinsicLogicalHeight(child);
 }
 
 LayoutUnit LayoutFlexibleBox::mainAxisExtentForChild(const LayoutBox& child) const
 {
     return isHorizontalFlow() ? child.size().width() : child.size().height();
 }
 
-LayoutUnit LayoutFlexibleBox::mainAxisContentExtentForChild(const LayoutBox& child) const
+LayoutUnit LayoutFlexibleBox::mainAxisContentExtentForChildIncludingScrollbar(const LayoutBox& child) const
 {
-    return isHorizontalFlow() ? child.contentWidth() : child.contentHeight();
+    return isHorizontalFlow() ? child.contentWidth() + child.verticalScrollbarWidth() : child.contentHeight() + child.horizontalScrollbarHeight();
 }
 
 LayoutUnit LayoutFlexibleBox::crossAxisExtent() const
 {
     return isHorizontalFlow() ? size().height() : size().width();
 }
 
 LayoutUnit LayoutFlexibleBox::mainAxisExtent() const
 {
     return isHorizontalFlow() ? size().width() : size().height();
@@ skipping 1118 matching lines @@
         LayoutBox* child = flexItem.box;
 
         if (child->isOutOfFlowPositioned()) {
             prepareChildForPositionedLayout(*child);
             continue;
         }
 
         child->setMayNeedPaintInvalidation();
 
         setOverrideMainAxisContentSizeForChild(*child, flexItem.flexedContentSize);
-        if (flexItem.flexedContentSize != mainAxisContentExtentForChild(*child)) {
+        // The flexed content size and the override size include the scrollbar
+        // width, so we need to compare to the size including the scrollbar.
+        // TODO(cbiesinger): Should it include the scrollbar?
+        if (flexItem.flexedContentSize != mainAxisContentExtentForChildIncludingScrollbar(*child)) {
             child->setChildNeedsLayout(MarkOnlyThis);
         } else {
             // To avoid double applying margin changes in updateAutoMarginsInCrossAxis, we reset the margins here.
             resetAutoMarginsAndLogicalTopInCrossAxis(*child);
         }
         // We may have already forced relayout for orthogonal flowing children in computeInnerFlexBaseSizeForChild.
         bool forceChildRelayout = relayoutChildren && !m_relaidOutChildren.contains(child);
         if (child->isLayoutBlock() && toLayoutBlock(*child).hasPercentHeightDescendants()) {
             // Have to force another relayout even though the child is sized correctly, because
             // its descendants are not sized correctly yet. Our previous layout of the child was
@@ skipping 277 matching lines @@
             DCHECK(child);
             LayoutUnit lineCrossAxisExtent = lineContexts[lineNumber].crossAxisExtent;
             LayoutUnit originalOffset = lineContexts[lineNumber].crossAxisOffset - crossAxisStartEdge;
             LayoutUnit newOffset = contentExtent - originalOffset - lineCrossAxisExtent;
             adjustAlignmentForChild(*child, newOffset - originalOffset);
         }
     }
 }
 
 } // namespace blink