static delay(seconds, realSetTimeout) {
    return new Promise(((resolve, reject) => {
      const timeout = realSetTimeout || setTimeout;
      timeout(() => {
        resolve();
      }, seconds * 1000.0);
    }));
  }
Returns a Promise which is resolved after the given delay.

@param {number} seconds The delay in seconds.
@param {function(function(), number)=} realSetTimeout
@return {!Promise}