Add WebMediaPlayer::timelineOffset() support to WebMediaPlayerImpl.

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 2985e74137d65bcc73abaacf0a4229338fd50774..14018da92939473527ba60876743d47b8c4e627d 100644
--- a/media/ffmpeg/ffmpeg_common.h
+++ b/media/ffmpeg/ffmpeg_common.h
@@ -110,6 +110,11 @@ VideoFrame::Format PixelFormatToVideoFormat(PixelFormat pixel_format);
 // Converts video formats to its corresponding FFmpeg's pixel formats.
 PixelFormat VideoFormatToPixelFormat(VideoFrame::Format video_format);
 
+// Convert FFmpeg UTC representation (YYYY-MM-DD HH:MM:SS) to base::Time.
+// Returns true and sets |*out| if |date_utc| contains a valid
+// date string. Otherwise returns fals and timeline_offset is unmodified.
+MEDIA_EXPORT bool FFmpegUTCDateToTime(const char* date_utc, base::Time* out);
+
 }  // namespace media
 
 #endif  // MEDIA_FFMPEG_FFMPEG_COMMON_H_