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

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

 /*
  * Copyright (C) 2012 Apple Inc.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 346 matching lines @@
 
     m_blockOffsetInEnclosingFlowThread = enclosingFlowThread() ? multiColumnBlockFlow()->offsetFromLogicalTopOfFirstPage() : LayoutUnit();
 
     for (LayoutBox* columnBox = firstMultiColumnBox(); columnBox; columnBox = columnBox->nextSiblingMultiColumnBox()) {
         if (!columnBox->isLayoutMultiColumnSet()) {
             ASSERT(columnBox->isLayoutMultiColumnSpannerPlaceholder()); // no other type is expected.
             m_needsColumnHeightsRecalculation = true;
             continue;
         }
         LayoutMultiColumnSet* columnSet = toLayoutMultiColumnSet(columnBox);
+        layoutScope.setChildNeedsLayout(columnSet);
         if (!m_inBalancingPass) {
             // This is the initial layout pass. We need to reset the column height, because contents
             // typically have changed.
             columnSet->resetColumnHeight();
         }
         if (!m_needsColumnHeightsRecalculation)
             m_needsColumnHeightsRecalculation = columnSet->heightIsAuto();
     }
 
     invalidateColumnSets();
     layout();
 }
 
 bool LayoutMultiColumnFlowThread::recalculateColumnHeights()
 {
     // All column sets that needed layout have now been laid out, so we can finally validate them.
     validateColumnSets();
 
     if (!m_needsColumnHeightsRecalculation)
         return false;
 
     // Column heights may change here because of balancing. We may have to do multiple layout
     // passes, depending on how the contents is fitted to the changed column heights. In most
     // cases, laying out again twice or even just once will suffice. Sometimes we need more
     // passes than that, though, but the number of retries should not exceed the number of
     // columns, unless we have a bug.
     bool needsRelayout = false;
-    for (LayoutMultiColumnSet* multicolSet = firstMultiColumnSet(); multicolSet; multicolSet = multicolSet->nextSiblingMultiColumnSet()) {
+    for (LayoutMultiColumnSet* multicolSet = firstMultiColumnSet(); multicolSet; multicolSet = multicolSet->nextSiblingMultiColumnSet())
         needsRelayout |= multicolSet->recalculateColumnHeight(m_inBalancingPass ? StretchBySpaceShortage : GuessFromFlowThreadPortion);
-        if (needsRelayout) {
-            // Once a column set gets a new column height, that column set and all successive column
-            // sets need to be laid out over again, since their logical top will be affected by
-            // this, and therefore their column heights may change as well, at least if the multicol
-            // height is constrained.
-            multicolSet->setChildNeedsLayout(MarkOnlyThis);
-        }
-    }
 
     if (needsRelayout)
         setChildNeedsLayout(MarkOnlyThis);
 
     m_inBalancingPass = needsRelayout;
     return needsRelayout;
 }
 
 void LayoutMultiColumnFlowThread::columnRuleStyleDidChange()
 {
@@ skipping 124 matching lines @@
                 insertBeforeColumnBox = firstMultiColumnBox();
             } else if (LayoutMultiColumnSpannerPlaceholder* previousPlaceholder = containingColumnSpannerPlaceholder(previousLayoutObject)) {
                 // Before us is another spanner. We belong right after it then.
                 insertBeforeColumnBox = previousPlaceholder->nextSiblingMultiColumnBox();
             } else {
                 // We're inside regular column content with both feet. Find out which column
                 // set this is. It needs to be split it into two sets, so that we can insert
                 // a new spanner placeholder between them.
                 setToSplit = mapDescendantToColumnSet(previousLayoutObject);
                 ASSERT(setToSplit == mapDescendantToColumnSet(insertedBeforeInFlowThread));
-                setToSplit->setNeedsLayoutAndFullPaintInvalidation(LayoutInvalidationReason::ColumnsChanged);
                 insertBeforeColumnBox = setToSplit->nextSiblingMultiColumnBox();
                 // We've found out which set that needs to be split. Now proceed to
                 // inserting the spanner placeholder, and then insert a second column set.
             }
         }
         ASSERT(setToSplit || insertBeforeColumnBox);
     }
 
     LayoutBlockFlow* multicolContainer = multiColumnBlockFlow();
     LayoutMultiColumnSpannerPlaceholder* newPlaceholder = LayoutMultiColumnSpannerPlaceholder::createAnonymous(multicolContainer->styleRef(), *spannerObjectInFlowThread);
     ASSERT(!insertBeforeColumnBox || insertBeforeColumnBox->parent() == multicolContainer);
     multicolContainer->LayoutBlock::addChild(newPlaceholder, insertBeforeColumnBox);
     spannerObjectInFlowThread->setSpannerPlaceholder(*newPlaceholder);
 
     if (setToSplit)
         createAndInsertMultiColumnSet(insertBeforeColumnBox);
 }
 
 void LayoutMultiColumnFlowThread::destroySpannerPlaceholder(LayoutMultiColumnSpannerPlaceholder* placeholder)
 {
     if (LayoutBox* nextColumnBox = placeholder->nextSiblingMultiColumnBox()) {
         LayoutBox* previousColumnBox = placeholder->previousSiblingMultiColumnBox();
         if (nextColumnBox && nextColumnBox->isLayoutMultiColumnSet()
             && previousColumnBox && previousColumnBox->isLayoutMultiColumnSet()) {
             // Need to merge two column sets.
             nextColumnBox->destroy();
-            previousColumnBox->setNeedsLayout(LayoutInvalidationReason::ColumnsChanged);
             invalidateColumnSets();
         }
     }
     placeholder->destroy();
 }
 
 bool LayoutMultiColumnFlowThread::descendantIsValidColumnSpanner(LayoutObject* descendant) const
 {
     // This method needs to behave correctly in the following situations:
     // - When the descendant doesn't have a spanner placeholder but should have one (return true)
@@ skipping 370 matching lines @@
     appendNewFragmentainerGroupIfNeeded(logicalTopInFlowThreadAfterPagination);
 }
 
 void LayoutMultiColumnFlowThread::updateMinimumPageHeight(LayoutUnit offset, LayoutUnit minHeight)
 {
     if (LayoutMultiColumnSet* multicolSet = columnSetAtBlockOffset(offset))
         multicolSet->updateMinimumColumnHeight(offset, minHeight);
 }
 
 }