dictionary HTMLMediaStreamConstraints {
  MediaTrackConstraintSet video;
  MediaTrackConstraintSet audio;
};

[Exposed=Window]
interface HTMLUserMediaElement : HTMLElement {
  [HTMLConstructor] constructor();

  attribute EventHandler onstream;
  attribute EventHandler oncancel;
  attribute EventHandler onerror;

  readonly attribute MediaStream? stream;
  readonly attribute DOMException? error;

  undefined setConstraints(optional HTMLMediaStreamConstraints constraints = {});
};