Google appears to have started rolling out a new device security feature called on-body detection. Basically, this feature uses your device’s accelerometer to figure out if your phone is in your hand or in your pocket. If the feature detects that your phone is not in one of those two locations, it will automatically lock. Ideally, this means that if you forget your phone or leave it sitting on a table somewhere, it will lock and prevent nefarious thieves from gaining access.
The process is relatively simple. Once you unlock your phone, it will remain unlocked as long as it’s in your hand or pocket. Once the device is put down, however, it will automatically lock again. When you pick it up, you’ll be required to unlock it. For obvious reasons, the on-body detection feature can’t tell who’s holding the phone, but only if it’s being held or in a pocket.
The implication here is that a feature like on-body detection, when coupled with Google’s new Device Protection feature, will make it nearly impossible for anyone to ever gain access to an Android device that isn’t their own. Whether or not on-body detection works consistently enough remains to be seen, though.
On-body detection appears to be gradually rolling out now to users running Android 5.0 or newer with the latest version of the Play Services app. As with most Google rollouts, it could take a while to hit your device, so be patient.