message: Remove the unique ptr to simplify the code.
diff: @@ -1129,27 +1129,27 @@ const absl::flat_hash_map<string, std::vector<string>> whitelist_table = {
  "Tile", "Transpose", "InvertPermutation", "Unpack"}}};
  // clang-format on
  -std::unique_ptr<absl::flat_hash_set<string>> GetWhitelist() {
  +absl::flat_hash_set<string> GetWhitelist() {
  MarkForCompilationPassFlags* flags = GetMarkForCompilationPassFlags();
  - auto whitelist = absl::WrapUnique(new absl::flat_hash_set<string>());
  + absl::flat_hash_set<string> whitelist;
  for (auto s : absl::StrSplit(flags->tf_xla_ops_to_cluster, ",")) {
  if (s == "FUSIBLE") {
  for (auto pair : whitelist_table) {
  - whitelist->insert(pair.second.begin(), pair.second.end());
  + whitelist.insert(pair.second.begin(), pair.second.end());
  }
  } else if (whitelist_table.contains(s)) {
  auto v = whitelist_table.at(s);
  - whitelist->insert(v.begin(), v.end());
  + whitelist.insert(v.begin(), v.end());
  } else if (!s.empty()) {
  // Should be a user provided TF operation.
  - whitelist->insert(string(s));
  + whitelist.insert(string(s));
  }
  }
  - if (VLOG_IS_ON(2) && !whitelist->empty()) {
  - std::vector<string> vwhitelist(whitelist->begin(), whitelist->end());
  - std::sort(vwhitelist.begin(), vwhitelist.end());
  + if (VLOG_IS_ON(2) && !whitelist.empty()) {
  + std::vector<string> vwhitelist(whitelist.begin(), whitelist.end());
  + absl::c_sort(vwhitelist);
  VLOG(2) << "XLA clustering will only consider the following TF operations: "
  << absl::StrJoin(vwhitelist, " ");
  }
  @@ -1189,10 +1189,10 @@ Status MarkForCompilationPassImpl::FindCompilationCandidates() {
  auto whitelist = GetWhitelist();
  - auto vall_ops = XlaOpRegistry::GetAllRegisteredOps();
  + std::vector<string> vall_ops = XlaOpRegistry::GetAllRegisteredOps();
  absl::flat_hash_set<string> all_ops(vall_ops.begin(), vall_ops.end());
  // Check that user's provided TF operation really exists.
  - for (auto s = whitelist->begin(); s != whitelist->end(); ++s) {
  + for (auto s = whitelist.begin(); s != whitelist.end(); ++s) {
  if (!all_ops.contains(string(*s))) {
  return errors::InvalidArgument(
  "The operation '", *s,
  @@ -1237,7 +1237,7 @@ Status MarkForCompilationPassImpl::FindCompilationCandidates() {
  continue;
  }
  - if (whitelist->size() > 0 && !whitelist->contains(node->def().op())) {
  + if (whitelist.size() > 0 && !whitelist.contains(node->def().op())) {
  VLOG(1) << "Rejecting " << node->name()
  << " as it is not listed in --tf_xla_ops_to_cluster.";
  continue;
  