message: even OpKernel::ComputeAync have async completion, the kernel launch / or memory copy can be still launched in the same thread, this is especially true for _Send/_Recv or _HostSend/_HostRecv.
  add annotation will let use see which op had issued the memory copy.
diff: @@ -1877,7 +1877,7 @@ void ExecutorState::Process(TaggedNode tagged_node, int64 scheduled_nsec) {
  };
  nodestats::SetOpStart(stats);
  {
  - profiler::TraceMe activity(
  + profiler::AnnotatedTraceMe activity(
  [&] {
  return op_kernel->TraceString(
  &state->ctx, /*verbose=*/profiler::TfOpDetailsEnabled());
  