/usr/lib/firefox/ is in firefox-locale-ml 11.0+build1-0ubuntu4.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/firefox-addons/extensions/
/usr/lib/firefox-addons/extensions/langpack-ml@firefox.mozilla.org.xpi
/usr/lib/firefox/distribution/
/usr/lib/firefox/distribution/searchplugins/
/usr/lib/firefox/distribution/searchplugins/locale/
/usr/lib/firefox/distribution/searchplugins/locale/ml/
/usr/lib/firefox/distribution/searchplugins/locale/ml/bing.xml
/usr/lib/firefox/distribution/searchplugins/locale/ml/eBay-in.xml
/usr/lib/firefox/distribution/searchplugins/locale/ml/google.xml
/usr/lib/firefox/distribution/searchplugins/locale/ml/rediff.xml
/usr/lib/firefox/distribution/searchplugins/locale/ml/webdunia.xml
/usr/lib/firefox/distribution/searchplugins/locale/ml/wikipedia-ml.xml
/usr/lib/firefox/distribution/searchplugins/locale/ml/wikipedia.xml