message: Use 2-arg TraceMe constructor to prevent unnecessary StrCat computation when
  tracing is disabled.
diff: @@ -106,7 +106,7 @@ Status CapturedFunction::Create(
  Status CapturedFunction::Run(FunctionLibraryRuntime::Options f_opts,
  gtl::ArraySlice<Tensor> args,
  std::vector<Tensor>* rets, const string& prefix) {
  - port::Tracing::TraceMe activity(strings::StrCat(prefix, "::Run"));
  + port::Tracing::TraceMe activity(prefix, "::Run");
  Notification n;
  Status s;
  auto done_callback = [&n, &s](Status func_status) {
  