code: function updateTimer(element) {
    // If the element is playing and we haven't started a timer yet, do so now.
    // Also, if the element's selectedIndex changed for any reason, restart the
    // timer. This ensures that the timer restarts no matter why the selection
    // changes: it could have been us moving to the next slide because the timer
    // elapsed, or the user might have directly manipulated the selection, etc.
    if (element.state.playing &&
        (!element.state.timerTimeout || element.state.selectedIndex !== element.state.selectedIndexForTimer)) {
      restartTimer(element);
    } else if (!element.state.playing && element.state.timerTimeout) {
      clearTimer(element);
    }
  }
docs: Update the timer to match the element's `playing` state.