use-services

Requires the use of Services.jsm rather than Cc[].getService() where a service is already defined in Services.jsm.

Examples of incorrect code for this rule:

Cc["@mozilla.org/appshell/window-mediator;1"].getService(Ci.nsIWindowMediator);
Components.classes["@mozilla.org/toolkit/app-startup;1"].getService(Components.interfaces.nsIAppStartup);

Examples of correct code for this rule:

Services.wm.addListener()
Cc["@mozilla.org/uuid-generator;1"].getService(Ci.nsIUUIDGenerator)