window['googletag'].pubads().addEventListener('impressionViewable', function(event) {
            scope.queue_metric({type: 'slot_view', source_id: scope.db_obj.source_id, auction_id: bid.auctionId, div_id: event.slot.getSlotElementId(), slot_id: event.slot.getSlotId().getAdUnitPath()});
          });