Fix computation of min|max-content contribution of non-replaced blocks

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

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2007 David Smith (catfish.man@gmail.com)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) Research In Motion Limited 2010. 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
  * License as published by the Free Software Foundation; either
@@ skipping 2126 matching lines @@
         // If the child is an orthogonal flow, child's height determines the width, but the height is not available until layout.
         // http://dev.w3.org/csswg/css-writing-modes-3/#orthogonal-shrink-to-fit
         if (!child.needsLayout()) {
             minPreferredLogicalWidth = maxPreferredLogicalWidth = toLayoutBox(child).logicalHeight();
             return;
         }
         m_needsRecalcLogicalWidthAfterLayoutChildren = true;
         minPreferredLogicalWidth = maxPreferredLogicalWidth = toLayoutBox(child).computeLogicalHeightWithoutLayout();
         return;
     }
-    minPreferredLogicalWidth = child.minPreferredLogicalWidth();
-    maxPreferredLogicalWidth = child.maxPreferredLogicalWidth();
+
+    if (child.isLayoutBlock() && !child.isReplaced()) {
+        const Length& computedInlineSize = child.styleRef().logicalWidth();
+        LayoutBlock& blockChild = toLayoutBlock(child);
+        if (computedInlineSize.isFitContent() || computedInlineSize.isFillAvailable() || computedInlineSize.isAuto()
+            || (computedInlineSize.hasPercent() && !toLayoutBox(child).percentageLogicalHeightIsResolvable())) {
+            minPreferredLogicalWidth = blockChild.minPreferredLogicalWidth();
+            maxPreferredLogicalWidth = blockChild.maxPreferredLogicalWidth();
+        } else {
+            ASSERT(computedInlineSize.isMinContent() || computedInlineSize.isMaxContent() || computedInlineSize.isSpecified());

[mstensho (USE GERRIT), 2015/12/09 13:19:52]

This is heavy. Start with bogus initial values. Lay out. Calculate correct
values. Lay out again. There's no good way around that when we're dealing with
perpendicular writing modes (code further up), but it should not necessary to
lay out in order to calculate the correct min/max preferred logical widths just
because width is min-content or max-content.

Why don't we just set the correct values right away instead?

If width is max-content, use maximum preferred logical width as minimum
preferred logical width as well.

If width is min-content, use minimum preferred logical width as maximum
preferred logical width as well.

A simpler way of achieving what you want could be:

    minPreferredLogicalWidth = child.minPreferredLogicalWidth();
    maxPreferredLogicalWidth = child.maxPreferredLogicalWidth();
    const Length& computedInlineSize = child.styleRef().logicalWidth();
    if (computedInlineSize.isMaxContent())
        minPreferredLogicalWidth = maxPreferredLogicalWidth;
    else if (computedInlineSize.isMinContent())
        maxPreferredLogicalWidth = minPreferredLogicalWidth;

We'd still get it wrong for table cells and possibly other things (cases where
LayoutBlock::computeChildPreferredLogicalWidths() isn't used), but we can fix
that separately, later.

+            m_needsRecalcLogicalWidthAfterLayoutChildren = child.needsLayout();
+            minPreferredLogicalWidth = blockChild.logicalWidth();
+            maxPreferredLogicalWidth = blockChild.logicalWidth();
+        }
+    } else {
+        // TODO(svillar): we leave the original implementation as default fallback. Still need to specialcase
+        // some other situations: https://drafts.csswg.org/css-sizing/#intrinsic
+        minPreferredLogicalWidth = child.minPreferredLogicalWidth();
+        maxPreferredLogicalWidth = child.maxPreferredLogicalWidth();
+    }
+
     if (child.isLayoutBlock() && toLayoutBlock(child).needsRecalcLogicalWidthAfterLayoutChildren())
         m_needsRecalcLogicalWidthAfterLayoutChildren = true;
 }
 
 bool LayoutBlock::hasLineIfEmpty() const
 {
     if (!node())
         return false;
 
     if (node()->isRootEditableElement())
@@ skipping 753 matching lines @@
 void LayoutBlock::showLineTreeAndMark(const InlineBox* markedBox1, const char* markedLabel1, const InlineBox* markedBox2, const char* markedLabel2, const LayoutObject* obj) const
 {
     showLayoutObject();
     for (const RootInlineBox* root = firstRootBox(); root; root = root->nextRootBox())
         root->showLineTreeAndMark(markedBox1, markedLabel1, markedBox2, markedLabel2, obj, 1);
 }
 
 #endif
 
 } // namespace blink