/usr/share/doc/libonline-accounts-plugin-dev/changelog.Debian.gz is in libonline-accounts-plugin-dev 0.7+16.04.20160322-0ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libonline-accounts-plugin-dev/../ubuntu-system-settings-online-accounts/changelog.Debian.gz