Facebook CEO Mark Zuckerberg gestures while delivering the keynote address at the f8 Facebook Developer Conference Wednesday, April 30, 2014, in San Francisco. (AP Photo/Ben Margot)
Facebook CEO Mark Zuckerberg gestures while delivering the keynote address at the f8 Facebook Developer Conference Wednesday, April 30, 2014, in San Francisco. (AP Photo/Ben Margot)
Facebook CEO Mark Zuckerberg gestures while delivering the keynote address at the f8 Facebook Developer Conference Wednesday, April 30, 2014, in San Francisco. (AP Photo/Ben Margot)
Facebook CEO Mark Zuckerberg gestures while delivering the keynote address at the f8 Facebook Developer Conference Wednesday, April 30, 2014, in San Francisco. (AP Photo/Ben Margot)
Facebook CEO Mark Zuckerberg gestures while delivering the keynote address at the f8 Facebook Developer Conference Wednesday, April 30, 2014, in San Francisco. (AP Photo/Ben Margot)
Facebook CEO Mark Zuckerberg gestures while delivering the keynote address at the f8 Facebook Developer Conference Wednesday, April 30, 2014, in San Francisco. (AP Photo/Ben Margot)
Facebook CEO Mark Zuckerberg gestures while delivering the keynote address at the f8 Facebook Developer Conference Wednesday, April 30, 2014, in San Francisco. (AP Photo/Ben Margot)
Facebook CEO Mark Zuckerberg gestures while delivering the keynote address at the f8 Facebook Developer Conference Wednesday, April 30, 2014, in San Francisco. (AP Photo/Ben Margot)