cc: Do bitmap conversion for RasterBuffer in the worker thread.

cc/resources/raster_buffer.h

Index: cc/resources/raster_buffer.h
diff --git a/cc/resources/raster_buffer.h b/cc/resources/raster_buffer.h
new file mode 100644
index 0000000000000000000000000000000000000000..2f010853e8d886c7ffcb8d5659180e86ec145702
--- /dev/null
+++ b/cc/resources/raster_buffer.h
@@ -0,0 +1,25 @@
+// 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 CC_RESOURCES_RASTER_BUFFER_H_
+#define CC_RESOURCES_RASTER_BUFFER_H_
+
+#include "skia/ext/refptr.h"
+
+class SkCanvas;
+
+namespace cc {
+
+class RasterBuffer {
+ public:
+  virtual skia::RefPtr<SkCanvas> AcquireSkCanvas() = 0;
+  virtual void ReleaseSkCanvas(const skia::RefPtr<SkCanvas>& canvas) = 0;
+
+ protected:
+  virtual ~RasterBuffer() {}
+};
+
+}  // namespace cc
+
+#endif  // CC_RESOURCES_RASTER_BUFFER_H_