canProceed() {
    var now = goog.now();
    var cutoffTimestamp = now - api.RequestThrottle.PERIOD_OFFSET_;
    this.processedRequests_ =
        goog.array.filter(this.processedRequests_, function(requestTimestamp) {
          return requestTimestamp > cutoffTimestamp;
        });

    if (this.processedRequests_.length < this.maxRequestsPerMinute_) {
      this.processedRequests_.push(now);
      return true;
    }

    return false;
  }
Signals if the request can proceed.
@return {boolean} True if the request can proceed. Otherwise false.