/usr/ is in firefox-locale-gd 28.0+build2-0ubuntu2.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/
/usr/lib/firefox/
/usr/lib/firefox/distribution/
/usr/lib/firefox/distribution/searchplugins/
/usr/lib/firefox/distribution/searchplugins/locale/
/usr/lib/firefox/distribution/searchplugins/locale/gd/
/usr/lib/firefox/distribution/searchplugins/locale/gd/wikipedia-gd.xml
/usr/lib/firefox/distribution/searchplugins/locale/gd/google.xml
/usr/lib/firefox/distribution/searchplugins/locale/gd/yahoo-en-GB.xml
/usr/lib/firefox/distribution/searchplugins/locale/gd/duckduckgo.xml
/usr/lib/firefox/distribution/searchplugins/locale/gd/amazon-en-GB.xml
/usr/lib/firefox/distribution/searchplugins/locale/gd/faclair-beag.xml
/usr/lib/firefox/distribution/searchplugins/locale/gd/bbc-alba.xml
/usr/lib/firefox-addons/
/usr/lib/firefox-addons/extensions/
/usr/lib/firefox-addons/extensions/langpack-gd@firefox.mozilla.org.xpi
/usr/share/
/usr/share/doc/
/usr/share/doc/firefox-locale-gd/
/usr/share/doc/firefox-locale-gd/copyright
/usr/share/doc/firefox-locale-gd/changelog.Debian.gz