Google Chrome	70.0.3538.110

What steps will reproduce the problem?

    const video = document.createElement('video');
    video.src = 'http://techslides.com/demos/sample-videos/small.mp4'
    video.requestPictureInPicture()
    video.src = ''
    document.exitPictureInPicture()

What is the expected result?
Picture-in-Picture window closes and promise resolves.

What happens instead?
Picture-in-Picture window stays opened and promise is pending forever.