[CSS Grid Layout] Content Distribution support for grid.

Source/core/layout/LayoutGrid.h

 /*
  * Copyright (C) 2011 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 106 matching lines @@
     LayoutUnit startOfColumnForChild(const LayoutBox& child) const;
     LayoutUnit endOfColumnForChild(const LayoutBox& child) const;
     LayoutUnit columnPositionLeft(const LayoutBox&) const;
     LayoutUnit columnPositionRight(const LayoutBox&) const;
     LayoutUnit centeredColumnPositionForChild(const LayoutBox&) const;
     LayoutUnit columnPositionForChild(const LayoutBox&) const;
     LayoutUnit startOfRowForChild(const LayoutBox& child) const;
     LayoutUnit endOfRowForChild(const LayoutBox& child) const;
     LayoutUnit centeredRowPositionForChild(const LayoutBox&) const;
     LayoutUnit rowPositionForChild(const LayoutBox&) const;
-    LayoutUnit contentPositionAndDistributionColumnOffset(LayoutUnit availableFreeSpace, ContentPosition, ContentDistributionType, OverflowAlignment, unsigned numberOfItems) const;
-    LayoutUnit contentPositionAndDistributionRowOffset(LayoutUnit availableFreeSpace, ContentPosition, ContentDistributionType, OverflowAlignment, unsigned numberOfItems) const;
-    LayoutPoint findChildLogicalPosition(const LayoutBox&, LayoutSize contentAlignmentOffset) const;
+    void computeContentPositionAndDistributionRowOffset(LayoutUnit availableFreeSpace, unsigned numberOfGridTracks);
+    void computeContentPositionAndDistributionColumnOffset(LayoutUnit availableFreeSpace, unsigned numberOfGridTracks);
+    LayoutPoint findChildLogicalPosition(const LayoutBox&) const;
     GridCoordinate cachedGridCoordinate(const LayoutBox&) const;
 
     LayoutUnit gridAreaBreadthForChild(const LayoutBox& child, GridTrackSizingDirection, const Vector<GridTrack>&) const;
 
     virtual void paintChildren(const PaintInfo&, const LayoutPoint&) override;
     bool allowedToStretchLogicalHeightForChild(const LayoutBox& child) const;
     bool needToStretchChildLogicalHeight(const LayoutBox&) const;
     LayoutUnit childIntrinsicHeight(const LayoutBox&) const;
     LayoutUnit childIntrinsicWidth(const LayoutBox&) const;
     LayoutUnit intrinsicLogicalHeightForChild(const LayoutBox&) const;
@@ skipping 20 matching lines @@
         return m_grid.size();
     }
 
     bool hasDefiniteLogicalSize(GridTrackSizingDirection) const;
 
     typedef Vector<Vector<GridCell>> GridRepresentation;
     GridRepresentation m_grid;
     bool m_gridIsDirty;
     Vector<LayoutUnit> m_rowPositions;
     Vector<LayoutUnit> m_columnPositions;
+    LayoutUnit m_rowsPositionOffset;
+    LayoutUnit m_rowsDistributionOffset;
+    LayoutUnit m_columnsPositionOffset;
+    LayoutUnit m_columnsDistributionOffset;

[Julien - ping for review, 2015/04/15 14:14:00]

Why do we need those members? They seem like transient information that we need
during layout but not after. That means that they would be better off being
passed during layout (or factored into Grid.SizingData.

[jfernandez, 2015/04/16 17:03:38]

I've finally moved the fields into the GridSizingData structure. Actually, the
only reason why they have to be stored is that I need them in the
findChildLocation function to deal with RTL direction. 

     HashMap<const LayoutBox*, GridCoordinate> m_gridItemCoordinate;
     OrderIterator m_orderIterator;
     Vector<LayoutBox*> m_gridItemsOverflowingGridArea;
     HashMap<const LayoutBox*, size_t> m_gridItemsIndexesMap;
 };
 
 DEFINE_LAYOUT_OBJECT_TYPE_CASTS(LayoutGrid, isLayoutGrid());
 
 } // namespace blink
 
 #endif // LayoutGrid_h