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
index f1a04ca2a367ae5fb0fbbfbfd260c571211c60ab..c80f6e793772c95212ca06d3ba2d04fac73a0689 100644
--- a/cc/resources/raster_buffer.h
+++ b/cc/resources/raster_buffer.h
@@ -5,14 +5,17 @@
 #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() {}