applyRate_(newRate) {
    const oldRate = this.harness_.getRate();

    if (oldRate != newRate) {
      this.harness_.setRate(newRate);
    }

    return oldRate != newRate;
  }
If the new rate is different than the media element's playback rate, this
will change the playback rate. If the rate does not need to change, it will
not be set. This will avoid unnecessary ratechange events.

@param {number} newRate
@return {boolean}
@private