/usr/lib/rhythmbox/ is in rhythmbox-radio-browser 2.3.1-0ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/rhythmbox/plugins/
/usr/lib/rhythmbox/plugins/radio-browser/
/usr/lib/rhythmbox/plugins/radio-browser/board_handler.py
/usr/lib/rhythmbox/plugins/radio-browser/feed.py
/usr/lib/rhythmbox/plugins/radio-browser/icecast_handler.py
/usr/lib/rhythmbox/plugins/radio-browser/local_handler.py
/usr/lib/rhythmbox/plugins/radio-browser/radio-browser.py
/usr/lib/rhythmbox/plugins/radio-browser/radio-browser.rb-plugin
/usr/lib/rhythmbox/plugins/radio-browser/radio_browser_source.py
/usr/lib/rhythmbox/plugins/radio-browser/radio_station.py
/usr/lib/rhythmbox/plugins/radio-browser/radiotime_handler.py
/usr/lib/rhythmbox/plugins/radio-browser/record_process.py
/usr/lib/rhythmbox/plugins/radio-browser/shoutcast_handler.py