[New Multicolumn] Use the term "content run" in favor of "forced break".

Source/core/rendering/RenderMultiColumnSet.h

 /*
  * 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 47 matching lines @@
 
     RenderBlockFlow* multiColumnBlockFlow() const { return toRenderBlockFlow(parent()); }
     RenderMultiColumnFlowThread* multiColumnFlowThread() const
     {
         ASSERT_WITH_SECURITY_IMPLICATION(!flowThread() || flowThread()->isRenderMultiColumnFlowThread());
         return static_cast<RenderMultiColumnFlowThread*>(flowThread());
     }
 
     RenderMultiColumnSet* nextSiblingMultiColumnSet() const;
 
+    LayoutUnit logicalTopInFlowThread() const { return isHorizontalWritingMode() ? flowThreadPortionRect().y() : flowThreadPortionRect().x(); }
     LayoutUnit logicalBottomInFlowThread() const { return isHorizontalWritingMode() ? flowThreadPortionRect().maxY() : flowThreadPortionRect().maxX(); }
 
     unsigned computedColumnCount() const { return m_computedColumnCount; }
     LayoutUnit computedColumnWidth() const { return m_computedColumnWidth; }
     LayoutUnit computedColumnHeight() const { return m_computedColumnHeight; }
 
     void setComputedColumnWidthAndCount(LayoutUnit width, unsigned count)
     {
         m_computedColumnWidth = width;
         m_computedColumnCount = count;
     }
 
     // Find the column that contains the given block offset, and return the translation needed to
     // get from flow thread coordinates to visual coordinates.
     LayoutSize flowThreadTranslationAtOffset(LayoutUnit) const;
 
     LayoutUnit heightAdjustedForSetOffset(LayoutUnit height) const;
 
     void updateMinimumColumnHeight(LayoutUnit height) { m_minimumColumnHeight = std::max(height, m_minimumColumnHeight); }
     LayoutUnit minimumColumnHeight() const { return m_minimumColumnHeight; }
 
-    unsigned forcedBreaksCount() const { return m_contentRuns.size(); }
-    void clearForcedBreaks();
-    void addForcedBreak(LayoutUnit offsetFromFirstPage);
+    // Add a content run, specified by its end position. A content run is appended at every
+    // forced/explicit break and at the end of the column set. The content runs are used to
+    // determine where implicit/soft breaks will occur, in order to calculate an initial column
+    // height.
+    void addContentRun(LayoutUnit endOffsetFromFirstPage);
 
     // (Re-)calculate the column height if it's auto. If 'initial' is set, guess an initial column
     // height; otherwise, stretch the column height a tad. Return true if column height changed and
     // another layout pass is required.
     bool recalculateColumnHeight(bool initial);
 
     // Record space shortage (the amount of space that would have been enough to prevent some
     // element from being moved to the next column) at a column break. The smallest amount of space
     // shortage we find is the amount with which we will stretch the column height, if it turns out
     // after layout that the columns weren't tall enough.
@@ skipping 60 matching lines @@
     LayoutUnit m_computedColumnWidth; // Used column width (the resulting 'W' from the pseudo-algorithm in the multicol spec)
     LayoutUnit m_computedColumnHeight;
 
     // The following variables are used when balancing the column set.
     LayoutUnit m_maxColumnHeight; // Maximum column height allowed.
     LayoutUnit m_minSpaceShortage; // The smallest amout of space shortage that caused a column break.
     LayoutUnit m_minimumColumnHeight;
 
     // A run of content without explicit (forced) breaks; i.e. a flow thread portion between two
     // explicit breaks, between flow thread start and an explicit break, between an explicit break
-    // and flow thread end, or, in cases when there are no explicit breaks at all: between flow flow
-    // thread start and flow thread end. We need to know where the explicit breaks are, in order to
-    // figure out where the implicit breaks will end up, so that we get the columns properly
-    // balanced. A content run starts out as representing one single column, and will represent one
-    // additional column for each implicit break "inserted" there.
+    // and flow thread end, or, in cases when there are no explicit breaks at all: between flow
+    // thread portion start and flow thread portion end. We need to know where the explicit breaks
+    // are, in order to figure out where the implicit breaks will end up, so that we get the columns
+    // properly balanced. A content run starts out as representing one single column, and will
+    // represent one additional column for each implicit break "inserted" there.
     class ContentRun {
     public:
         ContentRun(LayoutUnit breakOffset)
             : m_breakOffset(breakOffset)
             , m_assumedImplicitBreaks(0) { }
 
         unsigned assumedImplicitBreaks() const { return m_assumedImplicitBreaks; }
         void assumeAnotherImplicitBreak() { m_assumedImplicitBreaks++; }
         LayoutUnit breakOffset() const { return m_breakOffset; }
 
         // Return the column height that this content run would require, considering the implicit
         // breaks assumed so far.
         LayoutUnit columnLogicalHeight(LayoutUnit startOffset) const { return ceilf((m_breakOffset - startOffset).toFloat() / float(m_assumedImplicitBreaks + 1)); }
 
     private:
         LayoutUnit m_breakOffset; // Flow thread offset where this run ends.
         unsigned m_assumedImplicitBreaks; // Number of implicit breaks in this run assumed so far.
     };
     Vector<ContentRun, 1> m_contentRuns;
 };
 
 DEFINE_RENDER_OBJECT_TYPE_CASTS(RenderMultiColumnSet, isRenderMultiColumnSet());
 
 } // namespace WebCore
 
 #endif // RenderMultiColumnSet_h