PluckLock

Immediately lock your phone if someone snatches it from your hand. It pings the
accelerometer in the background and will lock the phone if the sum of all
non-gravitational forces ever exceeds the threshold.

Note that uninstallation is currently not obvious - you first need to
deactivate, in Android's Settings -> Security - Device Administrators. Until you
do this, uninstallation will fail.

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