Merge the background paint phase into the foreground phase.

sky/engine/core/rendering/PaintPhase.h

 /*
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  *           (C) 2000 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  *           (C) 2004 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 20 matching lines @@
 /*
  *  The painting of a layer occurs in three distinct phases.  Each phase involves
  *  a recursive descent into the layer's render objects. The first phase is the background phase.
  *  The backgrounds and borders of all blocks are painted.  Inlines are not painted at all.
  *  Floats must paint above block backgrounds but entirely below inline content that can overlap them.
  *  In the foreground phase, all inlines are fully painted.  Inline replaced elements will get all
  *  three phases invoked on them during this phase.
  */
 
 enum PaintPhase {
-    PaintPhaseBlockBackground,
-    PaintPhaseChildBlockBackground,
-    PaintPhaseChildBlockBackgrounds,
     PaintPhaseForeground,
     PaintPhaseOutline,
     PaintPhaseChildOutlines,
     PaintPhaseSelfOutline,
     PaintPhaseSelection,
     PaintPhaseMask,
 };
 
 } // namespace blink
 
 #endif  // SKY_ENGINE_CORE_RENDERING_PAINTPHASE_H_