function test() { // simple test to confirm we have chrome privileges let hasPrivileges = true; // this will throw an exception if we are not running with privileges try { var prefs = Components.classes["@mozilla.org/preferences-service;1"]. getService(Components.interfaces.nsIPrefBranch); } catch (e) { hasPrivileges = false; } // if we get here, we must have chrome privileges ok(hasPrivileges, "running with chrome privileges"); }