/usr/share/gtk-doc/html/ is in libnautilus-extension-dev 1:3.18.4.is.3.14.3-0ubuntu4.
This file is owned by root:root, with mode 0o755.
..
/usr/share/gtk-doc/html/libnautilus-extension/
/usr/share/gtk-doc/html/libnautilus-extension/ch01.html
/usr/share/gtk-doc/html/libnautilus-extension/home.png
/usr/share/gtk-doc/html/libnautilus-extension/index.html
/usr/share/gtk-doc/html/libnautilus-extension/index.sgml
/usr/share/gtk-doc/html/libnautilus-extension/ix01.html
/usr/share/gtk-doc/html/libnautilus-extension/left-insensitive.png
/usr/share/gtk-doc/html/libnautilus-extension/left.png
/usr/share/gtk-doc/html/libnautilus-extension/libnautilus-extension-nautilus-column-provider.html
/usr/share/gtk-doc/html/libnautilus-extension/libnautilus-extension-nautilus-column.html
/usr/share/gtk-doc/html/libnautilus-extension/libnautilus-extension-nautilus-extension-types.html
/usr/share/gtk-doc/html/libnautilus-extension/libnautilus-extension-nautilus-file-info.html
/usr/share/gtk-doc/html/libnautilus-extension/libnautilus-extension-nautilus-info-provider.html
/usr/share/gtk-doc/html/libnautilus-extension/libnautilus-extension-nautilus-location-widget-provider.html
/usr/share/gtk-doc/html/libnautilus-extension/libnautilus-extension-nautilus-menu-provider.html
/usr/share/gtk-doc/html/libnautilus-extension/libnautilus-extension-nautilus-menu.html
/usr/share/gtk-doc/html/libnautilus-extension/libnautilus-extension-nautilus-property-page-provider.html
/usr/share/gtk-doc/html/libnautilus-extension/libnautilus-extension-nautilus-property-page.html
/usr/share/gtk-doc/html/libnautilus-extension/libnautilus-extension.devhelp2
/usr/share/gtk-doc/html/libnautilus-extension/pt01.html
/usr/share/gtk-doc/html/libnautilus-extension/right-insensitive.png
/usr/share/gtk-doc/html/libnautilus-extension/right.png
/usr/share/gtk-doc/html/libnautilus-extension/style.css
/usr/share/gtk-doc/html/libnautilus-extension/up-insensitive.png
/usr/share/gtk-doc/html/libnautilus-extension/up.png