function retryRequest(): void {
      const retryDelay = _retryDelays[requestsAttempted - 1];
      const retryStartTime = requestStartTime + retryDelay;
      // Schedule retry for a configured duration after last request started.
      setTimeout(sendTimedRequest, retryStartTime - Date.now());
    }
Schedules another run of sendTimedRequest based on how much time has
passed between the time the last request was sent and now.