Flowers had told NFL.com's Around The NFL podcast earlier this week that San Diego was his top option, according to an NFL.com report.
The seven-year NFL veteran signed a one-year contract last year with San Diego. He logged three interceptions and 48 tackles over 14 games.
He spent the first six seasons of his career playing for the Kansas City Chiefs.
The Chargers will look to improve on the AFC's sixth-best defense in terms of total yards, but the second-worst defense in terms of yards-per-play given up.
San Diego finished 9-7 last season and missed the playoffs.