First version of new merge algorithm (not enabled yet)

Source/core/paint/BlockPainter.cpp

Index: Source/core/paint/BlockPainter.cpp
diff --git a/Source/core/paint/BlockPainter.cpp b/Source/core/paint/BlockPainter.cpp
index fef4a3f30189edd43202c91caaaa04f14aee3a43..fe273b2837b1d2c961cc1ff1a752ba1bb626c009 100644
--- a/Source/core/paint/BlockPainter.cpp
+++ b/Source/core/paint/BlockPainter.cpp
@@ -18,6 +18,7 @@
 #include "core/paint/RenderDrawingRecorder.h"
 #include "core/paint/ScrollRecorder.h"
 #include "core/paint/ScrollableAreaPainter.h"
+#include "core/paint/SubtreeInfoRecorder.h"
 #include "core/rendering/PaintInfo.h"
 #include "core/rendering/RenderBlock.h"
 #include "core/rendering/RenderFlexibleBox.h"
@@ -33,6 +34,7 @@ namespace blink {
 void BlockPainter::paint(const PaintInfo& paintInfo, const LayoutPoint& paintOffset)
 {
     PaintInfo localPaintInfo(paintInfo);
+    SubtreeInfoRecorder subtreeInfoRecorder(paintInfo.context, m_renderBlock, localPaintInfo.phase);

[chrishtr, 2015/02/03 22:30:47]

Just to be sure, this is just one example right?

[Xianzhu, 2015/02/04 00:13:24]

Yes. This looks the most common case of subtree painting. Adding of this code
can be incremental. For other subtree painting code if any, we'll repaint the
subtree when it appears the next time.

I'll find other places and add this code, perhaps in later changes.

 
     ANNOTATE_GRAPHICS_CONTEXT(localPaintInfo, &m_renderBlock);
 
@@ -51,6 +53,8 @@ void BlockPainter::paint(const PaintInfo& paintInfo, const LayoutPoint& paintOff
             return;
     }
 
+    subtreeInfoRecorder.begin();
+
     // There are some cases where not all clipped visual overflow is accounted for.
     // FIXME: reduce the number of such cases.
     ContentsClipBehavior contentsClipBehavior = ForceContentsClip;