tickEvery(seconds) {
    this.stop();

    if (goog.DEBUG) {
      // Capture the stack trace by making a fake error.
      const stackTrace = Error('Timer created').stack;
      shaka.util.Timer.activeTimers.set(this, stackTrace);
    }
    this.ticker_ = new shaka.util.DelayedTick(() => {
      // Schedule the timer again first. |onTick_| could cancel the timer and
      // rescheduling first simplifies the implementation.
      this.ticker_.tickAfter(seconds);
      this.onTick_();
    }).tickAfter(seconds);

    return this;
  }
Have the timer call |onTick| every |seconds| until |stop| is called.

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