message: Fix compilation error with clang.
  Link to breaking CI build:
diff: @@ -147,7 +147,7 @@ int main(int argc, char** argv) {
  tensorflow::string session_id =
  tensorflow::tpu::GetCurrentTimeStampAsString();
  constexpr char kProfilePluginDirectory[] = "plugins/profile/";
  - string repository_root =
  + tensorflow::string repository_root =
  ::tensorflow::io::JoinPath(FLAGS_logdir, kProfilePluginDirectory);
  while (true) {
  std::cout << "Starting to profile TPU traces for " << duration_ms << " ms. "
  