This is a DayDream (Screen Saver) widget which shows your Facebook's pictures.
This App works from Android 4.2+
To enable go to Setings->Display->DayDream and select Instadream DayDream. If you have it set in "when to daydream" menu and have your phone in the charger/dock it will not turn off its screen but displays this screensaver instead.
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