Create PaintChunk and begin writing code to build paint chunks.

third_party/WebKit/Source/platform/graphics/paint/PaintChunker.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 PaintChunker_h
+#define PaintChunker_h
+
+#include "platform/PlatformExport.h"
+#include "platform/graphics/paint/PaintChunk.h"
+#include "platform/graphics/paint/PaintProperties.h"
+#include "wtf/Vector.h"
+
+namespace blink {
+
+// Accepts information about changes to |PaintProperties| as drawings are
+// accumulated, and produces a series of paint chunks: contiguous ranges of the
+// display list with identical |PaintProperties|.
+class PLATFORM_EXPORT PaintChunker {
+public:
+    PaintChunker();
+    ~PaintChunker();
+
+    bool isInInitialState() const { return m_chunks.isEmpty() && m_currentProperties == PaintProperties(); }
+
+    void updateCurrentPaintProperties(const PaintProperties&);
+
+    void incrementDisplayItemIndex();
+    void decrementDisplayItemIndex();
+
+    // Releases the generated paint chunk list and resets the state of this
+    // object.
+    Vector<PaintChunk> releasePaintChunks();
+
+private:
+    Vector<PaintChunk> m_chunks;
+    PaintProperties m_currentProperties;
+};
+
+} // namespace blink
+
+#endif // PaintChunker_h