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

cc/resources/raster_buffer.h

+// 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_
+
+class SkCanvas;
+
+namespace cc {
+
+class RasterBuffer {
+ public:
+  virtual SkCanvas* GetSkCanvas() = 0;
+  virtual void Flush() = 0;

[reveman, 2014/08/11 20:32:36]

How about Acquire/ReleaseSkCanvas()? Acquire can allocate a temporary buffer and
Release will perform format conversion if necessary. We could potentially add
other functions that can be implemented without a temporary buffer. ie. Clear.

[auygun, 2014/08/12 13:36:35]

Done.

+
+ protected:
+  RasterBuffer();

[reveman, 2014/08/11 20:32:36]

you don't need this for fully abstract class.

[auygun, 2014/08/12 13:36:35]

Done.

+  virtual ~RasterBuffer();

[reveman, 2014/08/11 20:32:36]

you can add an empty implementation here and remove the .cc file:
virtual ~RasterBuffer() {}

[auygun, 2014/08/12 13:36:35]

Done.

+};
+
+}  // namespace cc
+
+#endif  // CC_RESOURCES_RASTER_BUFFER_H_