Google “Smart Lock” is in the process of being rebranded to “Extend Unlock”. This rebranding has started to roll out for a few users, but the rollout is incomplete since the Extend Unlock settings page is empty (likely the right server-side flag isn’t toggled for these users), Issue Tracker report.
Screenshots of the blank “Extend Unlock” settings page (courtesy Diablo0090, HydroPetro). If you want to know why Smart Lock is being rebranded to Extend Unlock, we talked about it sometime before.