publish(logRecord) {
    let target = this;
    while (target) {
      target.handlers.forEach(handler => {
        handler(logRecord);
      });
      target = target.parent;
    }
  }
Calls the log handlers associated with this Logger, followed by those of
its parents, etc. until the root Logger's associated log handlers are
called.
@param {!goog.log.LogRecord} logRecord The log record to pass to each
    handler.