Once the flow thread needs layout, mark all column sets for layout as well.

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

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 
 #include "core/layout/MultiColumnFragmentainerGroup.h"
 
 #include "core/layout/ColumnBalancer.h"
 #include "core/layout/LayoutMultiColumnSet.h"
@@ skipping 36 matching lines @@
     return isLastGroup() && m_columnSet.heightIsAuto();
 }
 
 void MultiColumnFragmentainerGroup::resetColumnHeight()
 {
     // Nuke previously stored minimum column height. Contents may have changed for all we know.
     m_minimumColumnHeight = 0;
 
     m_maxColumnHeight = calculateMaxColumnHeight();
 
-    LayoutUnit oldColumnHeight = m_columnHeight;
-
     LayoutMultiColumnFlowThread* flowThread = m_columnSet.multiColumnFlowThread();
     LayoutMultiColumnFlowThread* enclosingFlowThread = flowThread->enclosingFlowThread();
     if (enclosingFlowThread && enclosingFlowThread->isPageLogicalHeightKnown()) {
         // TODO(mstensho): Do this better. If height is auto here, we shouldn't set a
         // height, or forced breaks and pagination struts might mess up column balancing.
         LayoutUnit columnHeight = heightIsAuto() ? m_maxColumnHeight : heightAdjustedForRowOffset(flowThread->columnHeightAvailable());
         setAndConstrainColumnHeight(columnHeight);
     } else if (heightIsAuto()) {
         m_columnHeight = LayoutUnit();
     } else {
         setAndConstrainColumnHeight(heightAdjustedForRowOffset(flowThread->columnHeightAvailable()));
     }
-
-    if (m_columnHeight != oldColumnHeight)
-        m_columnSet.setChildNeedsLayout(MarkOnlyThis);
 }
 
 bool MultiColumnFragmentainerGroup::recalculateColumnHeight(BalancedColumnHeightCalculation calculationMode)
 {
     LayoutUnit oldColumnHeight = m_columnHeight;
 
     m_maxColumnHeight = calculateMaxColumnHeight();
 
     if (heightIsAuto()) {
         LayoutUnit newColumnHeight = calculateColumnHeight(calculationMode);
@@ skipping 477 matching lines @@
     append(MultiColumnFragmentainerGroup(m_columnSet));
     return last();
 }
 
 void MultiColumnFragmentainerGroupList::deleteExtraGroups()
 {
     shrink(1);
 }
 
 } // namespace blink