/usr/share/doc/chromium-codecs-ffmpeg-extra-dbg/changelog.Debian.gz is in chromium-codecs-ffmpeg-extra-dbg 34.0.1847.116-0ubuntu2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/chromium-codecs-ffmpeg-extra-dbg/../chromium-codecs-ffmpeg-extra/changelog.Debian.gz