[New Multicolumn] Support for paged overflow.

Source/core/rendering/RenderMultiColumnFlowThread.h

Index: Source/core/rendering/RenderMultiColumnFlowThread.h
diff --git a/Source/core/rendering/RenderMultiColumnFlowThread.h b/Source/core/rendering/RenderMultiColumnFlowThread.h
index ff5784835b121b9b127f4074265b78e8c6edceb1..634883cbb4662b371382acb8f43a49c72a2dffd0 100644
--- a/Source/core/rendering/RenderMultiColumnFlowThread.h
+++ b/Source/core/rendering/RenderMultiColumnFlowThread.h
@@ -111,20 +111,25 @@ public:
     unsigned columnCount() const { return m_columnCount; }
     LayoutUnit columnHeightAvailable() const { return m_columnHeightAvailable; }
     void setColumnHeightAvailable(LayoutUnit available) { m_columnHeightAvailable = available; }
-    bool requiresBalancing() const { return !columnHeightAvailable() || multiColumnBlockFlow()->style()->columnFill() == ColumnFillBalance; }
+    virtual bool heightIsAuto() const { return !columnHeightAvailable() || multiColumnBlockFlow()->style()->columnFill() == ColumnFillBalance; }
+    bool progressionIsInline() const { return m_progressionIsInline; }
 
     virtual LayoutSize columnOffset(const LayoutPoint&) const OVERRIDE FINAL;
 
     // Do we need to set a new width and lay out?
-    bool needsNewWidth() const;
+    virtual bool needsNewWidth() const;
 
     void layoutColumns(bool relayoutChildren, SubtreeLayoutScope&);
 
     bool recalculateColumnHeights();
 
-private:
+protected:
     RenderMultiColumnFlowThread();
+    void setProgressionIsInline(bool isInline) { m_progressionIsInline = isInline; }
+
+    virtual void layout() OVERRIDE;
 
+private:
     void calculateColumnCountAndWidth(LayoutUnit& width, unsigned& count) const;
 
     virtual const char* renderName() const OVERRIDE;
@@ -132,7 +137,6 @@ private:
     virtual void willBeRemovedFromTree() OVERRIDE;
     virtual void computeLogicalHeight(LayoutUnit logicalHeight, LayoutUnit logicalTop, LogicalExtentComputedValues&) const OVERRIDE;
     virtual void updateLogicalWidth() OVERRIDE FINAL;
-    virtual void layout() OVERRIDE FINAL;
     virtual void setPageBreak(LayoutUnit offset, LayoutUnit spaceShortage) OVERRIDE;
     virtual void updateMinimumPageHeight(LayoutUnit offset, LayoutUnit minHeight) OVERRIDE;
     virtual RenderRegion* regionAtBlockOffset(LayoutUnit) const OVERRIDE;
@@ -143,6 +147,7 @@ private:
     LayoutUnit m_columnHeightAvailable; // Total height available to columns, or 0 if auto.
     bool m_inBalancingPass; // Set when relayouting for column balancing.
     bool m_needsColumnHeightsRecalculation; // Set when we need to recalculate the column set heights after layout.
+    bool m_progressionIsInline; // Always true for regular multicol. False for paged-y overflow.
 };
 
 } // namespace WebCore