rewind_() {
    if (!this.video.duration) {
      return;
    }

    const trickPlayRate = this.player.getPlaybackRate();
    const newRateIndex = this.rewindRates_.indexOf(trickPlayRate) + 1;

    // When the button is clicked, the next rate in this.rewindRates_ is
    // selected. If no more rates are available, the first one is set.
    const newRate = (newRateIndex != this.rewindRates_.length) ?
        this.rewindRates_[newRateIndex] : this.rewindRates_[0];

    if (this.video.paused) {
      // Our fast forward is implemented with playbackRate and needs the video
      // to be playing (to not be paused) to take immediate effect.
      // If the video is paused, "unpause" it.
      this.video.play();
    }
    this.player.trickPlay(newRate);

    this.button_.setAttribute('shaka-status', newRate + 'x');
  }
Cycles trick play rate between the selected rewind rates.
@private