At the moment the PiP window will capture media keys on CrOS if it is open before passing to a WebContents. If we switch on media key delegation this will (kind of) break. The PiP window will only get media keys if the underlying tab has audio focus. We should think about how PiP should interact with audio focus (i.e. whether we should close a pip window if another session gains focus, or whether we should block other sessions from gaining focus).