Revert of Change the video color space default.

media/ffmpeg/ffmpeg_common.h

Index: media/ffmpeg/ffmpeg_common.h
diff --git a/media/ffmpeg/ffmpeg_common.h b/media/ffmpeg/ffmpeg_common.h
index 86e074217d832b0b4cf7a09231d37d9a915a6165..a73fddd3716a49ae42a416519527c6f665a02257 100644
--- a/media/ffmpeg/ffmpeg_common.h
+++ b/media/ffmpeg/ffmpeg_common.h
@@ -117,15 +117,12 @@
 MEDIA_EXPORT SampleFormat
     AVSampleFormatToSampleFormat(AVSampleFormat sample_format);
 
-// Converts FFmpeg's pixel format to its corresponding supported video format.
+// Converts FFmpeg's pixel formats to its corresponding supported video format.
 MEDIA_EXPORT VideoFrame::Format PixelFormatToVideoFormat(
     PixelFormat pixel_format);
 
-// Converts video formats to its corresponding FFmpeg pixel formats.
+// Converts video formats to its corresponding FFmpeg's pixel formats.
 PixelFormat VideoFormatToPixelFormat(VideoFrame::Format video_format);
-
-VideoFrame::ColorSpace AVColorSpaceToVideoFrameColorSpace(
-    AVColorSpace color_space);
 
 // Convert FFmpeg UTC representation (YYYY-MM-DD HH:MM:SS) to base::Time.
 // Returns true and sets |*out| if |date_utc| contains a valid