Jump to the next outer column when an inner column is too short.

third_party/WebKit/Source/core/layout/LayoutFlowThread.h

 /*
  * Copyright (C) 2011 Adobe Systems Incorporated. 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.
@@ skipping 71 matching lines @@
     void invalidateColumnSets();
     bool hasValidColumnSetInfo() const { return !m_columnSetsInvalidated && !m_multiColumnSetList.isEmpty(); }
 
     void mapRectToPaintInvalidationBacking(const LayoutBoxModelObject* paintInvalidationContainer, LayoutRect&, const PaintInvalidationState*) const override;
 
     LayoutUnit pageLogicalHeightForOffset(LayoutUnit);
     LayoutUnit pageRemainingLogicalHeightForOffset(LayoutUnit, PageBoundaryRule);
 
     virtual void contentWasLaidOut(LayoutUnit logicalTopInFlowThreadAfterPagination) = 0;
 
+    // Find and return the next logical top after |flowThreadOffset| that can fit unbreakable
+    // content as tall as |contentLogicalHeight|. |flowThreadOffset| is expected to be at the exact
+    // top of a column. This method is called when the current column is too short to fit the
+    // content, in the hope that there exists one that's tall enough further ahead. If no such
+    // column can be found, |flowThreadOffset| will be returned.
+    LayoutUnit nextLogicalTopForUnbreakableContent(LayoutUnit flowThreadOffset, LayoutUnit contentLogicalHeight) const;
+
     virtual bool isPageLogicalHeightKnown() const { return true; }
     bool pageLogicalSizeChanged() const { return m_pageLogicalSizeChanged; }
 
     void collectLayerFragments(PaintLayerFragments&, const LayoutRect& layerBoundingBox, const LayoutRect& dirtyRectInFlowThread);
 
     // Return the visual bounding box based on the supplied flow-thread bounding box. Both
     // rectangles are completely physical in terms of writing mode.
     LayoutRect fragmentsBoundingBox(const LayoutRect& layerBoundingBox) const;
 
     LayoutPoint flowThreadPointToVisualPoint(const LayoutPoint& flowThreadPoint) const
@@ skipping 45 matching lines @@
 // These structures are used by PODIntervalTree for debugging.
 #ifndef NDEBUG
 template <> struct ValueToString<LayoutMultiColumnSet*> {
     static String string(const LayoutMultiColumnSet* value) { return String::format("%p", value); }
 };
 #endif
 
 } // namespace blink
 
 #endif // LayoutFlowThread_h