We could do a better job of coordinating media playback and event handling if the UIProcess took responsibility for tracking some media state. Right now the MediaSession information is controlled in the WebProcess. However, since individual WebProcess processes do not know about other WebProcess instances, we don't always do the right thing when resuming playback, since it boils down to a race between the different paused processes to see who gets started first. If the UIProcess took responsibility for this, we could always resume playback in the right state.