Slimming Paint phase 2 compositing algorithm plumbing

Source/core/compositing/DisplayListCompositingBuilder.h

+// 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 DisplayListCompositingBuilder_h
+#define DisplayListCompositingBuilder_h
+
+#include "core/CoreExport.h"
+#include "platform/graphics/paint/DisplayItemList.h"
+#include "platform/graphics/paint/DisplayItemTransformTree.h"
+
+namespace blink {
+
+struct CompositedDisplayList {
+    // TODO(pdr): Also add our SimpleLayers here.
+    // TODO(pdr): Add the additional property trees (e.g., clip, scroll, etc).
+    OwnPtr<const DisplayItemTransformTree> transformTree;
+};
+
+class CORE_EXPORT DisplayListCompositingBuilder {
+public:
+    DisplayListCompositingBuilder(const DisplayItemList& displayItemList, const DisplayListDiff&)
+        : m_displayItemList(displayItemList) { }
+
+    void build(CompositedDisplayList&);
+
+private:
+    const DisplayItemList& m_displayItemList;
+};
+
+} // namespace blink
+
+#endif // DisplayListCompositingBuilder_h