David Marcus, vice president of messaging products for Facebook Inc., speaks during the F8 Developer Conference in San Jose, California, U.S., on Tuesday, April 18, 2017. During his keynote, Facebook CEO Mark Zuckerberg laid out his strategy for augmented reality, saying the social network will use smartphone cameras to overlay virtual items on the real world rather than waiting for AR glasses to be technically possible. Photographer: David Paul Morris/Bloomberg via Getty Images