[css-flexbox] align-content should apply even when there's just a single line

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

Index: third_party/WebKit/Source/core/layout/LayoutFlexibleBox.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutFlexibleBox.cpp b/third_party/WebKit/Source/core/layout/LayoutFlexibleBox.cpp
index dc2278b9f51f64d1ef5fd56b50cc0bd3f673827f..feffbf8b2ab90cff37852e419f63960549f9eac6 100644
--- a/third_party/WebKit/Source/core/layout/LayoutFlexibleBox.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutFlexibleBox.cpp
@@ -1734,9 +1734,9 @@ void LayoutFlexibleBox::layoutColumnReverse(const OrderedFlexItemList& children,
     }
 }
 
-static LayoutUnit initialAlignContentOffset(LayoutUnit availableFreeSpace, ContentPosition alignContent, ContentDistributionType alignContentDistribution, unsigned numberOfLines)
+static LayoutUnit initialAlignContentOffset(LayoutUnit availableFreeSpace, ContentPosition alignContent, ContentDistributionType alignContentDistribution, bool isMultiline, unsigned numberOfLines)
 {
-    if (numberOfLines <= 1)
+    if (!isMultiline)
         return LayoutUnit();
     if (alignContent == ContentPositionFlexEnd)
         return availableFreeSpace;
@@ -1764,13 +1764,15 @@ static LayoutUnit alignContentSpaceBetweenChildren(LayoutUnit availableFreeSpace
 
 void LayoutFlexibleBox::alignFlexLines(Vector<LineContext>& lineContexts)
 {
+    if (!lineContexts.size())
+        return;
+
     ContentPosition position = styleRef().resolvedAlignContentPosition(normalValueBehavior());
     ContentDistributionType distribution = styleRef().resolvedAlignContentDistribution(normalValueBehavior());
 
-    // If we have a single line flexbox or a multiline line flexbox with only one flex line,
-    // the line height is all the available space.
+    // If we have a single line flexbox the line height is all the available space.
     // For flex-direction: row, this means we need to use the height, so we do this after calling updateLogicalHeight.
-    if (lineContexts.size() == 1) {
+    if (!isMultiline()) {
         lineContexts[0].crossAxisExtent = crossAxisContentExtent();
         return;
     }
@@ -1783,7 +1785,7 @@ void LayoutFlexibleBox::alignFlexLines(Vector<LineContext>& lineContexts)
         availableCrossAxisSpace -= lineContexts[i].crossAxisExtent;
 
     LayoutBox* child = m_orderIterator.first();
-    LayoutUnit lineOffset = initialAlignContentOffset(availableCrossAxisSpace, position, distribution, lineContexts.size());
+    LayoutUnit lineOffset = initialAlignContentOffset(availableCrossAxisSpace, position, distribution, isMultiline(), lineContexts.size());
     for (unsigned lineNumber = 0; lineNumber < lineContexts.size(); ++lineNumber) {
         lineContexts[lineNumber].crossAxisOffset += lineOffset;
         for (size_t childNumber = 0; childNumber < lineContexts[lineNumber].numberOfChildren; ++childNumber, child = m_orderIterator.next())