@Override
 public int getUniqueURLCount() {
   return xHistoryParticleManager.getUniqueURLCount();
 }
 @Override
 public List<HistoryUrl> getUrlPosition() {
   return xHistoryParticleManager.getUrlPosition();
 }
 @Override
 public XIHistoryParticle getLastParticleInCollection() {
   return xHistoryParticleManager.getLastParticle();
 }