code: function getTransfers(queue) {
      var transfers = [];
      var fnArray = queue.fnArray, argsArray = queue.argsArray;
      for (var i = 0, ii = queue.length; i < ii; i++) {
        switch (fnArray[i]) {
          case OPS.paintInlineImageXObject:
          case OPS.paintInlineImageXObjectGroup:
          case OPS.paintImageMaskXObject:
            var arg = argsArray[i][0]; // first param in imgData
            if (!arg.cached) {
              transfers.push(arg.data.buffer);
            }
            break;
        }
      }
      return transfers;
    }
docs: close to chunk size