tickAfter(seconds) {
    this.stop();

    this.ticker_ = new shaka.util.DelayedTick(() => {
      this.onTick_();
    }).tickAfter(seconds);

    return this;
  }
Have the timer call |onTick| after |seconds| has elapsed unless |stop| is
called first.

@param {number} seconds
@return {!shaka.util.Timer}
@export