message: Use OP_REQUIRES_OK_ASYNC in the MakeIteratorOp async kernel
diff: @@ -402,10 +402,12 @@ Status AnonymousIteratorHandleOp::CreateResource(
  void MakeIteratorOp::ComputeAsync(OpKernelContext* ctx, DoneCallback done) {
  DatasetBase* dataset;
  - OP_REQUIRES_OK(ctx, GetDatasetFromVariantTensor(ctx->input(0), &dataset));
  + OP_REQUIRES_OK_ASYNC(
  + ctx, GetDatasetFromVariantTensor(ctx->input(0), &dataset), done);
  IteratorResource* iterator_resource;
  - OP_REQUIRES_OK(
  - ctx, LookupResource(ctx, HandleFromInput(ctx, 1), &iterator_resource));
  + OP_REQUIRES_OK_ASYNC(
  + ctx, LookupResource(ctx, HandleFromInput(ctx, 1), &iterator_resource),
  + done);
  background_worker_.Schedule(std::bind(
  [ctx, iterator_resource, dataset](DoneCallback done) {
  Status s = iterator_resource->SetIteratorFromDataset(ctx, dataset);
  