nsICookieService in Firefox 3.5

 nsICookieService

 Provides methods for setting and getting cookies in the context of a
 page load.  See nsICookieManager for methods to manipulate the cookie
 database directly.  This separation of interface is mainly historical.

 This service broadcasts the following notifications when the cookie
 list is changed, or a cookie is rejected:

 topic  : "cookie-changed"
          broadcast whenever the cookie list changes in some way. there
          are four possible data strings for this notification; one
          notification will be broadcast for each change, and will involve
          a single cookie.
 subject: an nsICookie2 interface pointer representing the cookie object
          that changed.
 data   : "deleted"
          a cookie was deleted. the subject is the deleted cookie.
          "added"
          a cookie was added. the subject is the added cookie.
          "changed"
          a cookie was changed. the subject is the new cookie.
          "cleared"
          the entire cookie list was cleared. the subject is null.

 topic  : "cookie-rejected"
          broadcast whenever a cookie was rejected from being set as a
          result of user prefs.
 subject: an nsIURI interface pointer representing the URI that attempted
          to set the cookie.
 data   : none.