According to WSWS.org,
The banned pages include highly popular postings by groups opposing and publicizing incidents of police violence such as Police the Police, Cop Block and Filming Cops [...]
RT also seems to corroborate that (but it's likely that this is WSWS's source). RT also lists "Cop Logic" a site that highlights and documents “the absurd and unpredictable antics of cops” across the globe was deleted?