Google's new indoor maps stuff is implemented at the map layer. They don't have the infrastructure in place to track your wifi from a location's sensors and the

Google's new indoor maps stuff is implemented at the map layer. They don't have the infrastructure in place to track your wifi from a location's sensors and then communicate that back to the phone. It's just whatever physical-location technology is already built into your phone (typically some combination of GPS, cellular, and a list of what wifi access points are available), plus an indoor floorplan.