SAN FRANCISCO – Mask slackers will now have to provide photographic proof they're wearing a face covering before boarding an Uber.The San Francisco-based company unveiled a new policy Tuesday stipulating that if a driver reports to Uber that a rider wasn’t wearing a mask, the rider will have to provide Uber with a selfie with one strapped on the next time they summon a car on the world’s largest ride-hailing service.The mask verification rule expands upon a similar requirement that Uber imposed on its drivers in May to help reassure passengers worried about being exposed to the novel coronavirus that has upended society.