New display item caching

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..0de9c371a63aaac0ece5cf3e28c60d40f2dacaab
--- /dev/null
+++ b/Source/core/paint/SubtreeInfoRecorder.h
@@ -0,0 +1,36 @@
+// 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 "platform/graphics/paint/DisplayItem.h"
+
+namespace blink {
+
+class DisplayItemList;
+class GraphicsContext;
+class RenderObject;
+
+class SubtreeInfoRecorder {
+public:
+    SubtreeInfoRecorder(GraphicsContext*, const RenderObject&, PaintPhase);
+
+    ~SubtreeInfoRecorder();
+
+    void begin();
+
+private:
+    void addDisplayItem(PassOwnPtr<DisplayItem>);
+
+    DisplayItemList* m_displayItemList;
+    const RenderObject& m_renderer;
+    const DisplayItem::Type m_displayItemType;
+    bool m_begun;
+};
+
+} // namespace blink
+
+#endif // SubtreeInfoRecorder_h