message: load_stats: fix for Google import.
  Risk level: Low
  Testing: OSS/Google unit/integration tests for LRS.
diff: @@ -120,8 +120,11 @@ void LoadStatsReporter::onReceiveMessage(
  void LoadStatsReporter::startLoadReportPeriod() {
  // Once a cluster is tracked, we don't want to reset its stats between reports
  // to avoid racing between request/response.
  - std::unordered_map<absl::string_view, std::chrono::steady_clock::duration, StringViewHash>
  - existing_clusters;
  + // TODO(htuch): They key here could be absl::string_view, but this causes
  + // problems due to referencing of temporaries in the below loop with Google's
  + // internal string type. Consider this optimization when the string types
  + // converge.
  + std::unordered_map<std::string, std::chrono::steady_clock::duration> existing_clusters;
  for (const std::string& cluster_name : message_->clusters()) {
  if (clusters_.count(cluster_name) > 0) {
  existing_clusters.emplace(cluster_name, clusters_[cluster_name]);
  