playPausePresentation() {
    if (!this.enabled_) {
      return;
    }

    if (this.ad_) {
      this.playPauseAd();
      if (this.ad_.isLinear()) {
        return;
      }
    }

    if (!this.video_.duration) {
      // Can't play yet.  Ignore.
      return;
    }

    if (this.presentationIsPaused()) {
      // If we are at the end, go back to the beginning.
      if (this.player_.isEnded()) {
        this.video_.currentTime = this.player_.seekRange().start;
      }
      this.video_.play();
    } else {
      this.video_.pause();
    }
  }
Play or pause the current presentation.