void queryUsageAndQuota(int storageType, [StorageUsageCallback usageCallback(int currentUsageInBytes, int currentQuotaInBytes), StorageErrorCallback errorCallback(DomError error)])

Source 

void queryUsageAndQuota(int storageType, [StorageUsageCallback usageCallback, StorageErrorCallback errorCallback]) {
  if (errorCallback != null) {
    _blink.BlinkDeprecatedStorageInfo.instance.queryUsageAndQuota_Callback_3_(this, storageType, usageCallback, errorCallback);
    return;
  }
  if (usageCallback != null) {
    _blink.BlinkDeprecatedStorageInfo.instance.queryUsageAndQuota_Callback_2_(this, storageType, usageCallback);
    return;
  }
  _blink.BlinkDeprecatedStorageInfo.instance.queryUsageAndQuota_Callback_1_(this, storageType);
  return;
}