code: public function onCollectionLoad(Varien_Event_Observer $observer)
      {
          if (!$this->canCollect()) {
              return;
          }
  
          /** @var Mage_Core_Model_Resource_Db_Collection_Abstract */
          $collection = $observer->getData('collection');
          $this->getRequestInfo()->addCollection($collection);
      }
docs: Listens to core_collection_abstract_load_before and eav_collection_abstract_load_before events
  and records loaded collections
  
  @param Varien_Event_Observer $observer