code: public function onControllerFrontSendResponseAfter(Varien_Event_Observer $observer)
      {
          if (!$this->canCollect()) {
              return;
          }
  
          /** @var Mage_Core_Controller_Varien_Front $front */
          $front = $observer->getData('front');
  
          $this->updateProfiling();
          $this->getRequestInfo()->getController()->addResponseInfo($front->getResponse());
      }
docs: Listens to controller_front_send_response_after. This event represents the end of a request.
  
  @param Varien_Event_Observer $observer