If /etc/opt/ is required by FHS, then shouldn't base-files own /etc/opt/ ? I'm beginning to suspect that the problem here isn't chrome-gnome-shell (see #888549) or Google Chrome or piuparts or these in-house apps, but base-files for creating a directory in its postinst instead of creating it in the usual way and owning the directory so that dpkg won't remove the directory when uninstalling the last file in the directory.
For archaeological reference, /etc/opt/ was added to base-files as a result of #118505. Thanks, Jeremy Bicha
