Refactor scaling.

webrtc/common_video/include/video_frame_buffer.h

Index: webrtc/common_video/include/video_frame_buffer.h
diff --git a/webrtc/common_video/include/video_frame_buffer.h b/webrtc/common_video/include/video_frame_buffer.h
index 984bd50d674e78d7e7aedfc252fcfef8810b6963..311af01ce7f884bf56f8a509bf86d5e1b2d55eab 100644
--- a/webrtc/common_video/include/video_frame_buffer.h
+++ b/webrtc/common_video/include/video_frame_buffer.h
@@ -109,6 +109,23 @@ class I420Buffer : public VideoFrameBuffer {
   static rtc::scoped_refptr<I420Buffer> Copy(
       const rtc::scoped_refptr<VideoFrameBuffer>& buffer);
 
+  // Only the most generally useful operations should be methods on

[perkj_webrtc, 2016/06/02 13:43:08]

I don't think this comment belong here. please remove. 

[nisse-webrtc, 2016/06/03 13:55:02]

Done.

+  // this class, for more specialized operations, use
+  // MutableDataY(,U,V) to get write access.
+
+  // Scale the cropped area of |src|, writing into this buffer.

[perkj_webrtc, 2016/06/02 13:43:08]

Please comment that the result width and height will be the size of the this
buffer.

[nisse-webrtc, 2016/06/03 13:55:02]

Done.

+  void CropAndScale(const rtc::scoped_refptr<VideoFrameBuffer>& src,
+                    int offset_x,
+                    int offset_y,
+                    int crop_width,
+                    int crop_height);
+
+  // The common case of a center crop, when needed to maintain the
+  // same aspect ratio.
+  static void CenterCropAndScale(

[perkj_webrtc, 2016/06/02 13:43:08]

I would prefer this to be just  
void CropAndScale(const rtc::scoped_refptr<VideoFrameBuffer>& src). There is no
need for this to be static.

[nisse-webrtc, 2016/06/03 13:55:02]

Done.

+      const rtc::scoped_refptr<I420Buffer>& dst,
+      const rtc::scoped_refptr<VideoFrameBuffer>& src);
+
  protected:
   ~I420Buffer() override;
 
@@ -186,13 +203,6 @@ class WrappedI420Buffer : public webrtc::VideoFrameBuffer {
   rtc::Callback0<void> no_longer_used_cb_;
 };
 
-// Helper function to crop |buffer| without making a deep copy. May only be used
-// for non-native frames.
-rtc::scoped_refptr<VideoFrameBuffer> ShallowCenterCrop(
-    const rtc::scoped_refptr<VideoFrameBuffer>& buffer,
-    int cropped_width,
-    int cropped_height);
-
 }  // namespace webrtc
 
 #endif  // WEBRTC_COMMON_VIDEO_INCLUDE_VIDEO_FRAME_BUFFER_H_