[css-flex] Implement the space-evenly content-distribution value

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

 /*
  * Copyright (C) 2011 Google 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 1521 matching lines @@
   if (data.GetPosition() == kContentPositionFlexEnd)
     return available_free_space;
   if (data.GetPosition() == kContentPositionCenter)
     return available_free_space / 2;
   if (data.Distribution() == kContentDistributionSpaceAround) {
     if (available_free_space > 0 && number_of_items)
       return available_free_space / (2 * number_of_items);
 
     return available_free_space / 2;
   }
+  if (data.Distribution() == kContentDistributionSpaceEvenly) {
+    if (available_free_space > 0 && number_of_items)
+      return available_free_space / (number_of_items + 1);
+    // Fallback to 'center'
+    return available_free_space / 2;
+  }
   return LayoutUnit();
 }
 
 static LayoutUnit ContentDistributionSpaceBetweenChildren(
     LayoutUnit available_free_space,
     const StyleContentAlignmentData& data,
     unsigned number_of_items) {
   if (available_free_space > 0 && number_of_items > 1) {
     if (data.Distribution() == kContentDistributionSpaceBetween)
       return available_free_space / (number_of_items - 1);
     if (data.Distribution() == kContentDistributionSpaceAround ||
         data.Distribution() == kContentDistributionStretch)
       return available_free_space / number_of_items;
+    if (data.Distribution() == kContentDistributionSpaceEvenly)
+      return available_free_space / (number_of_items + 1);
   }
   return LayoutUnit();
 }
 
 static LayoutUnit AlignmentOffset(LayoutUnit available_free_space,
                                   ItemPosition position,
                                   LayoutUnit ascent,
                                   LayoutUnit max_ascent,
                                   bool is_wrap_reverse) {
   switch (position) {
@@ skipping 613 matching lines @@
       LayoutUnit original_offset =
           line_contexts[line_number].cross_axis_offset - cross_axis_start_edge;
       LayoutUnit new_offset =
           content_extent - original_offset - line_cross_axis_extent;
       AdjustAlignmentForChild(*flex_item.box, new_offset - original_offset);
     }
   }
 }
 
 }  // namespace blink