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

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

Index: third_party/WebKit/Source/core/layout/LayoutBlock.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutBlock.cpp b/third_party/WebKit/Source/core/layout/LayoutBlock.cpp
index 0a7572f7a7f0e4aa2ec4a84f2e3f2b828c1c6118..356840210efd670620905492f9456e0805c76514 100644
--- a/third_party/WebKit/Source/core/layout/LayoutBlock.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutBlock.cpp
@@ -2144,8 +2144,27 @@ void LayoutBlock::computeChildPreferredLogicalWidths(LayoutObject& child, Layout
         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;
 }