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_
 
+#include "skia/ext/refptr.h"
+
 class SkCanvas;
 
 namespace cc {
 
 class RasterBuffer {
  public:
-  virtual SkCanvas* AcquireSkCanvas() = 0;
-  virtual void ReleaseSkCanvas() = 0;
+  virtual skia::RefPtr<SkCanvas> AcquireSkCanvas() = 0;

[reveman, 2014/08/13 19:19:49]

Do we need to return a skia::RefPtr? It's weird that Acquire returns a ref but
Release doesn't pass it back.

[auygun, 2014/08/14 10:35:42]

Isn't it better to pass around the skia::RefPtr instead of the raw pointer?
Let's have Release pass it back.

[reveman, 2014/08/14 12:26:36]

Use skia::RefPtr if you need to pass ownership. Raw pointer is preferred if
that's not the case. Looks like you need to pass ownership in this case though
so skia::RefPtr is then correct.

[auygun, 2014/08/15 09:20:40]

Acknowledged.

+  // Returns true if canvas was written to while acquired.
+  virtual bool ReleaseSkCanvas(SkCanvas* canvas) = 0;
 
  protected:
   virtual ~RasterBuffer() {}
 };
 
 }  // namespace cc
 
 #endif  // CC_RESOURCES_RASTER_BUFFER_H_