Slimming Paint phase 2 compositing algorithm plumbing & skeleton display list API.

public/platform/WebDisplayList.h

Index: public/platform/WebDisplayList.h
diff --git a/public/platform/WebDisplayList.h b/public/platform/WebDisplayList.h
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+// 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 WebDisplayList_h
+#define WebDisplayList_h
+
+#include "WebVector.h"
+#include "skia/ext/pixel_ref_utils.h"
+
+namespace blink {
+
+// TODO(chrishtr): this is just a placeholder for demonstration purposes, we should use the real class.
+class WebDisplayItem {
+public:
+    virtual ~WebDisplayItem() { }
+};
+
+// Represents the display list contents of a content layer.
+class WebDisplayList {
+public:
+    virtual ~WebDisplayList() { }
+    virtual unsigned size() const = 0;
+    virtual const WebDisplayItem& displayItem(unsigned index) const = 0;
+//  virtual const skia::DiscardablePixelRefList& pixelRefs() const  = 0;
+};
+
+} // namespace blink
+
+#endif // WebDisplayList_h