@alexgpg, А.. значит эту переменную я задавал, чтобы хромиум думал, что он дефолтный браузер. :) У меня все тут:
$ sed -n -e '/^\[Defa/,$p' ~/.local/share/applications/mimeapps.list
[Default Applications]
text/html=firefox.desktop
text/plain=gedit.desktop
x-scheme-handler/http=firefox.desktop
x-scheme-handler/https=firefox.desktop
x-scheme-handler/ftp=userapp-Firefox-ZCMBEW.desktop
x-scheme-handler/chrome=userapp-Firefox-ZCMBEW.desktop
application/x-extension-htm=userapp-Firefox-ZCMBEW.desktop
application/x-extension-html=userapp-Firefox-ZCMBEW.desktop
application/x-extension-shtml=userapp-Firefox-ZCMBEW.desktop
application/xhtml+xml=userapp-Firefox-ZCMBEW.desktop
application/x-extension-xhtml=userapp-Firefox-ZCMBEW.desktop
application/x-extension-xht=userapp-Firefox-ZCMBEW.desktop