The San Francisco 49ers announced Friday that they signed guard Laken Tomlinson to a three-year extension through the 2021 season.The deal is worth up to $18 million with $10 million guaranteed, according to the NFL Network.Tomlinson, 26, started 15 games for the 49ers last season after being acquired 10 months ago from the Detroit Lions.”Laken is a very talented player who has improved consistently since joining the team one week before last year’s season opener,” 49ers general manager John Lynch said in a statement. “This offseason, his hard work and dedication paid off as he continued to progress and performed at a high level. We were confident we could work out a contract extension with Laken and we are fired up to get that done before training camp.”Last month, the 49ers declined Tomlinson’s fifth-year option worth $9.625 million as the two sides continued toward reaching a deal.Tomlinson was the 28th overall selection by the Lions in the 2015 draft and started 24 of 32 games played before being traded to San Francisco.