Add unit test for stand-alone denoiser and fixed some bugs.

webrtc/video_frame.h

Index: webrtc/video_frame.h
diff --git a/webrtc/video_frame.h b/webrtc/video_frame.h
index 7ad0c328db2bac21700e4524dbc9baccb6605867..83d808391d1e755ea02a697915b160eb2251983d 100644
--- a/webrtc/video_frame.h
+++ b/webrtc/video_frame.h
@@ -158,6 +158,8 @@ class VideoFrame {
   // called on a non-native-handle frame.
   VideoFrame ConvertNativeToI420Frame() const;
 
+  bool EqualFrames(const VideoFrame& frame) const;
+
  private:
   // An opaque reference counted handle that stores the pixel data.
   rtc::scoped_refptr<webrtc::VideoFrameBuffer> video_frame_buffer_;