/usr/lib/ is in firefox-locale-mai 28.0+build2-0ubuntu2.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/firefox/
/usr/lib/firefox/distribution/
/usr/lib/firefox/distribution/searchplugins/
/usr/lib/firefox/distribution/searchplugins/locale/
/usr/lib/firefox/distribution/searchplugins/locale/mai/
/usr/lib/firefox/distribution/searchplugins/locale/mai/google.xml
/usr/lib/firefox/distribution/searchplugins/locale/mai/wikipedia-hi.xml
/usr/lib/firefox/distribution/searchplugins/locale/mai/twitter.xml
/usr/lib/firefox/distribution/searchplugins/locale/mai/eBay-in.xml
/usr/lib/firefox/distribution/searchplugins/locale/mai/duckduckgo.xml
/usr/lib/firefox/distribution/searchplugins/locale/mai/yahoo-in.xml
/usr/lib/firefox/distribution/searchplugins/locale/mai/bing.xml
/usr/lib/firefox-addons/
/usr/lib/firefox-addons/extensions/
/usr/lib/firefox-addons/extensions/langpack-mai@firefox.mozilla.org.xpi