Feature description: Geofencing allows apps to be notified (upon approval) once a user enters or exits a geofence. A geofence commonly is defined as a point (lat/long) with a radius.
 
Eng owner: tbd
Product owner: nattestad@

Design doc: there is an abandoned spec for the feature https://www.w3.org/TR/2015/WD-geofencing-20150604/ authored by mek@ and future work will happen on https://w3c.github.io/geolocation-sensor/.