nsINavHistoryObserver
void ondeleteuri(in nsiuri auri, in acstring aguid); void ondeletevisits(in nsiuri auri, in prtime avisittime, in acstring aguid); void onendupdatebatch(); void onpagechanged(in nsiuri auri, in unsigned long awhat, in astring avalue); void onpageexpired(in nsiuri auri, in prtime avisittime, in boolean awholeentry); obsolete since gecko 2.0 void ontitlechanged(in nsiuri auri, in astring apagetitle); void onvisit(in nsiuri auri, in long long avisitid, in prtime atime, in long long asessionid, in long long areferringid, in unsigned long atransitiontype, in acstring aguid, out unsigned long aadded); constants constant value description attribute_favicon 3 the page's favicon changed.
... ontitlechanged() called whenever either the real title or the custom title of the page changes.
...void ontitlechanged( in nsiuri auri, in astring apagetitle ); parameters auri the uri of the page whose title changed.

Places Developer Guide
getservice(ci.nsinavhistoryservice); let observer = { onbeginupdatebatch: function() { }, onendupdatebatch: function() { }, onvisit: function(auri, avisitid, atime, asessionid, areferringid, atransitiontype) { }, ontitlechanged: function(auri, apagetitle) { }, ondeleteuri: function(auri) { }, onclearhistory: function() { }, onpagechanged: function(auri, awhat, avalue) { }, onpageexpired: function(auri, avisittime, awholeentry) { }, queryinterface: function(iid) { if (iid.equals(components.interfaces.nsinavhistoryobserver) || iid.equals(components.interfaces.nsisupports)) { return th...