Optimize to copy from rotated video to canvas.

media/filters/skcanvas_video_renderer.h

 // Copyright (c) 2012 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 MEDIA_FILTERS_SKCANVAS_VIDEO_RENDERER_H_
 #define MEDIA_FILTERS_SKCANVAS_VIDEO_RENDERER_H_
 
 #include "base/memory/ref_counted.h"
 #include "base/time/time.h"
 #include "media/base/media_export.h"
 #include "media/base/video_rotation.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 #include "third_party/skia/include/core/SkXfermode.h"
 #include "ui/gfx/rect.h"
 
 class SkCanvas;
 
 namespace media {
 
 class VideoFrame;
 class VideoImageGenerator;
 
 // Handles rendering of VideoFrames to SkCanvases, doing any necessary YUV
 // conversion and caching of resulting RGB bitmaps.
 class MEDIA_EXPORT SkCanvasVideoRenderer {
  public:
   SkCanvasVideoRenderer();
   ~SkCanvasVideoRenderer();
 
-  // Paints |video_frame| on |canvas|, scaling the result to fit dimensions
-  // specified by |dest_rect|.
+  // Paints |video_frame| on |canvas|, scaling and rotating the result to fit
+  // dimensions specified by |dest_rect|.
   //
   // Black will be painted on |canvas| if |video_frame| is null.
   void Paint(const scoped_refptr<VideoFrame>& video_frame,
              SkCanvas* canvas,
              const gfx::RectF& dest_rect,
              uint8 alpha,
              SkXfermode::Mode mode,
              VideoRotation video_rotation);
 
   // Copy |video_frame| on |canvas|.
   void Copy(const scoped_refptr<VideoFrame>&, SkCanvas* canvas);
 
  private:
   VideoImageGenerator* generator_;
 
   // An RGB bitmap and corresponding timestamp of the previously converted
   // video frame data.
   SkBitmap last_frame_;
   base::TimeDelta last_frame_timestamp_;
 
   DISALLOW_COPY_AND_ASSIGN(SkCanvasVideoRenderer);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_FILTERS_SKCANVAS_VIDEO_RENDERER_H_