Delete unused and almost unused frame-related methods.

webrtc/common_video/video_frame.cc

Index: webrtc/common_video/video_frame.cc
diff --git a/webrtc/common_video/video_frame.cc b/webrtc/common_video/video_frame.cc
index bfac3a680de9fc18ace1dc323ce1b29d34655197..463e8ed44254a30829bde14e3c7bfe612b342533 100644
--- a/webrtc/common_video/video_frame.cc
+++ b/webrtc/common_video/video_frame.cc
@@ -155,20 +155,6 @@ const rtc::scoped_refptr<VideoFrameBuffer>& VideoFrame::video_frame_buffer()
   return video_frame_buffer_;
 }
 
-void VideoFrame::set_video_frame_buffer(
-    const rtc::scoped_refptr<webrtc::VideoFrameBuffer>& buffer) {
-  RTC_DCHECK(buffer);
-  video_frame_buffer_ = buffer;
-}
-
-VideoFrame VideoFrame::ConvertNativeToI420Frame() const {
-  RTC_DCHECK(video_frame_buffer_->native_handle());
-  VideoFrame frame;
-  frame.ShallowCopy(*this);
-  frame.set_video_frame_buffer(video_frame_buffer_->NativeToI420Buffer());
-  return frame;
-}
-
 size_t EncodedImage::GetBufferPaddingBytes(VideoCodecType codec_type) {
   switch (codec_type) {
     case kVideoCodecVP8: