Barker (Achilles) didn't receive a qualifying offer or minimum tender from the Browns and has become an unrestricted free agent, per the league's official transaction log.
The move doesn't come as any surprise after Barker spent the entire 2017 campaign on injured reserve due to a preseason Achilles injury. Considering he's coming off a major injury and has practically spent his entire career bouncing from practice squad to practice squad, it wouldn't be a total surprise if he opens the 2018 campaign unaffiliated with any NFL team.