Smart Lock in Lollipop encompasses both trusted face and trusted devices, but a new option is joining the party—trusted places. The latest Google Play Services for Lollipop devices is adding this option to the menu automagically. Just choose a trusted place, and your phone will remain unlocked when it's in that geographic area.
If you're on a Lollipop device and aren't seeing this yet, you can manually install the –438 build of Play Services 6.5 from APKMirror. After a restart, trusted places should be an option in Smart Lock. There are toggles for home and work locations, which are set through Google Maps, but I haven't been able to get these to work despite having my address in Maps—not sure what's up with that. You can still set a manual location, though.
Just like when you use a trusted Bluetooth device connection, trusted location bypasses the secure lock screen, but in this case when the device is within a few dozen meters of the chosen location. You can set multiple locations as well. You'll obviously need to have location services on for this to work.