Walk render tree instead of render layers for paint.

sky/engine/core/rendering/RenderParagraph.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef SKY_ENGINE_CORE_RENDERING_RENDERPARAGRAPH_H_
 #define SKY_ENGINE_CORE_RENDERING_RENDERPARAGRAPH_H_
 
 #include "sky/engine/core/dom/ContainerNode.h"
 #include "sky/engine/core/rendering/RenderBlockFlow.h"
 
@@ skipping 16 matching lines @@
     GapRects inlineSelectionGaps(RenderBlock* rootBlock, const LayoutPoint& rootBlockPhysicalPosition, const LayoutSize& offsetFromRootBlock,
         LayoutUnit& lastLogicalTop, LayoutUnit& lastLogicalLeft, LayoutUnit& lastLogicalRight, const PaintInfo*);
 
 protected:
     void layoutChildren(bool relayoutChildren, SubtreeLayoutScope&, LayoutUnit beforeEdge, LayoutUnit afterEdge) final;
 
     void addOverflowFromChildren() final;
 
     void simplifiedNormalFlowLayout() final;
 
-    void paintChildren(PaintInfo&, const LayoutPoint&) final;
+    void paintChildren(PaintInfo&, const LayoutPoint&, Vector<RenderBox*>& layers) final;
 
     bool hitTestContents(const HitTestRequest&, HitTestResult&, const HitTestLocation& locationInContainer, const LayoutPoint& accumulatedOffset, HitTestAction) final;
 
     virtual ETextAlign textAlignmentForLine(bool endsWithSoftBreak) const;
 
     void computeIntrinsicLogicalWidths(LayoutUnit& minLogicalWidth, LayoutUnit& maxLogicalWidth) const final;
 
     int firstLineBoxBaseline() const final;
     int lastLineBoxBaseline(LineDirectionMode) const final;
 
@@ skipping 21 matching lines @@
     bool matchedEndLine(LineLayoutState&, const InlineBidiResolver&, const InlineIterator& endLineStart, const BidiStatus& endLineStatus);
     void deleteEllipsisLineBoxes();
     void checkLinesForTextOverflow();
 };
 
 DEFINE_RENDER_OBJECT_TYPE_CASTS(RenderParagraph, isRenderParagraph());
 
 } // namespace blink
 
 #endif  // SKY_ENGINE_CORE_RENDERING_RENDERPARAGRAPH_H_