First version of new merge algorithm (not enabled yet)

Source/core/paint/SubtreeInfoRecorder.h

Index: Source/core/paint/SubtreeInfoRecorder.h
diff --git a/Source/core/paint/SubtreeInfoRecorder.h b/Source/core/paint/SubtreeInfoRecorder.h
new file mode 100644
index 0000000000000000000000000000000000000000..ef8449757e739850b50b3ea234a80c15a63dc1ef
--- /dev/null
+++ b/Source/core/paint/SubtreeInfoRecorder.h
@@ -0,0 +1,37 @@
+// Copyright 2015 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 SubtreeInfoRecorder_h
+#define SubtreeInfoRecorder_h
+
+#include "core/rendering/PaintPhase.h"
+#include "wtf/PassOwnPtr.h"
+
+namespace blink {
+
+class DisplayItem;
+class DisplayItemList;
+class GraphicsContext;
+class RenderObject;
+
+class SubtreeInfoRecorder {

[pdr., 2015/02/04 05:19:58]

Could you add a short comment here about what this is for?


I wonder if we should name this "StackingContextRecorder" since it maps to the
web painting algorithm's concept of a stacking context?

[chrishtr, 2015/02/04 07:08:14]

It's not quite the same as stacking context. It can refer to a subtree only
within a given phase, for example.

But I agree the class needs a comment.

[Xianzhu, 2015/02/04 20:46:32]

Done.

+public:
+    SubtreeInfoRecorder(GraphicsContext*, const RenderObject&, PaintPhase);
+
+    ~SubtreeInfoRecorder();
+
+    void begin();
+
+private:
+    void addDisplayItem(PassOwnPtr<DisplayItem>);
+
+    DisplayItemList* m_displayItemList;
+    const RenderObject& m_renderer;
+    const PaintPhase m_paintPhase;
+    bool m_begun;
+};
+
+} // namespace blink
+
+#endif // SubtreeInfoRecorder_h