Reimplement min-width: auto

Source/core/layout/LayoutFlexibleBox.cpp

Index: Source/core/layout/LayoutFlexibleBox.cpp
diff --git a/Source/core/layout/LayoutFlexibleBox.cpp b/Source/core/layout/LayoutFlexibleBox.cpp
index a30f5d91022e034adc4ec194e96b3591ff85a4cb..ea656b856e701a455f1bca733baf5463c6d75f65 100644
--- a/Source/core/layout/LayoutFlexibleBox.cpp
+++ b/Source/core/layout/LayoutFlexibleBox.cpp
@@ -419,7 +419,7 @@ LayoutUnit LayoutFlexibleBox::computeMainAxisExtentForChild(LayoutBox& child, Si
         // We don't have to check for "auto" here - computeContentLogicalHeight will just return -1 for that case anyway.
         if (size.isIntrinsic())
             child.layoutIfNeeded();
-        return child.computeContentLogicalHeight(size, child.logicalHeight() - child.borderAndPaddingLogicalHeight()) + child.scrollbarLogicalHeight();
+        return child.computeContentLogicalHeight(sizeType, size, child.logicalHeight() - child.borderAndPaddingLogicalHeight()) + child.scrollbarLogicalHeight();
     }
     return child.computeLogicalWidthUsing(sizeType, size, contentLogicalWidth(), this) - child.borderAndPaddingLogicalWidth();
 }
@@ -837,16 +837,48 @@ void LayoutFlexibleBox::prepareOrderIteratorAndMargins()
 LayoutUnit LayoutFlexibleBox::adjustChildSizeForMinAndMax(LayoutBox& child, LayoutUnit childSize)
 {
     Length max = isHorizontalFlow() ? child.style()->maxWidth() : child.style()->maxHeight();
+    LayoutUnit maxExtent = -1;
     if (max.isSpecifiedOrIntrinsic()) {
-        LayoutUnit maxExtent = computeMainAxisExtentForChild(child, MaxSize, max);
+        maxExtent = computeMainAxisExtentForChild(child, MaxSize, max);
         if (maxExtent != -1 && childSize > maxExtent)
             childSize = maxExtent;
     }
 
     Length min = isHorizontalFlow() ? child.style()->minWidth() : child.style()->minHeight();
     LayoutUnit minExtent = 0;
-    if (min.isSpecifiedOrIntrinsic())
+    if (min.isSpecifiedOrIntrinsic()) {
         minExtent = computeMainAxisExtentForChild(child, MinSize, min);
+        // computeMainAxisExtentForChild can return -1 when the child has a percentage
+        // min size, but we have an indefinite size in that axis.
+        minExtent = std::max(LayoutUnit(0), minExtent);
+    } else if (min.isAuto() && mainAxisOverflowForChild(child) == OVISIBLE) {
+        // css-flexbox section 4.5
+        LayoutUnit contentSize = computeMainAxisExtentForChild(child, MinSize, Length(MinContent));
+        ASSERT(contentSize >= 0);
+        if (maxExtent != -1 && contentSize > maxExtent)
+            contentSize = maxExtent;
+
+        bool hasClampedSize = !childPreferredMainAxisContentExtentRequiresLayout(child);
+        if (hasClampedSize) {
+            Length flexBasis = flexBasisForChild(child);

[Julien - ping for review, 2015/04/06 17:06:47]

const Length&?

[cbiesinger, 2015/04/06 21:34:16]

Done.

+            bool flexBasisIsDefinite = flexBasis.isFixed() || (flexBasis.isPercent() && mainAxisExtentIsDefinite());
+            if (flexBasisIsDefinite) {
+                LayoutUnit resolvedFlexBasis = computeMainAxisExtentForChild(child, MainOrPreferredSize, flexBasis);
+                ASSERT(resolvedFlexBasis >= 0);
+                LayoutUnit clampedSize = resolvedFlexBasis;

[Julien - ping for review, 2015/04/06 17:06:47]

We don't seem to need |resolvedFlexBasis| as we directly copy its value into
|clampedSize|.

[cbiesinger, 2015/04/06 21:34:16]

clampedSize is basically std::min(resolvedFlexBasis, maxExtent) -- the if below
modified it. Do you think it's too unclear?

[Julien - ping for review, 2015/04/13 21:25:59]

I think this would be clearer:

LayoutUnit clampedSize = maxExtent != -1 ? min(resolvedFlexBasis, maxExtent) :
resolvedFlexBasis;

[cbiesinger, 2015/04/13 23:23:12]

Done.

+                if (maxExtent != -1 && clampedSize > maxExtent)
+                    clampedSize = maxExtent;
+
+                minExtent = std::min(clampedSize, contentSize);
+            } else {
+                minExtent = contentSize;
+            }
+        } else {
+            minExtent = contentSize;
+        }
+        // TODO(cbiesinger): Implement aspect ratio handling (here, transferred size) - crbug.com/249112
+    }
+    ASSERT(minExtent >= 0);
     return std::max(childSize, minExtent);
 }
 
@@ -1058,6 +1090,13 @@ bool LayoutFlexibleBox::needToStretchChildLogicalHeight(LayoutBox& child) const
     return isHorizontalFlow() && child.style()->height().isAuto();
 }
 
+EOverflow LayoutFlexibleBox::mainAxisOverflowForChild(LayoutBox& child) const
+{
+    if (isHorizontalFlow())
+        return child.styleRef().overflowX();
+    return child.styleRef().overflowY();
+}
+
 void LayoutFlexibleBox::layoutAndPlaceChildren(LayoutUnit& crossAxisOffset, const OrderedFlexItemList& children, const Vector<LayoutUnit, 16>& childSizes, LayoutUnit availableFreeSpace, bool relayoutChildren, Vector<LineContext>& lineContexts)
 {
     ASSERT(childSizes.size() == children.size());