message: [XLA] Use the fast and lazy host callback to free tuple buffers
diff: @@ -53,7 +53,7 @@ Status GenericTransferManager::WriteSingleTupleIndexTable(
  TF_RETURN_IF_ERROR(TransferBufferToDevice(
  stream, GetByteSizeRequirement(shape), element_pointers->data(), region));
  // Ensure the buffer is transferred before we destroy element_pointers.
  - stream->ThenDoHostCallback([element_pointers]() {
  + stream->ThenRunAfterNextBlockHostUntilDone([element_pointers]() {
  /* holds reference to element_pointers in closure */
  });
  return Status::OK();
  