message: Set operation types to unknown for those ops without a type.
diff: @@ -35,8 +35,10 @@ class DeviceTfOpMetricsDbBuilder : public OpMetricsDbBuilder {
  const OpMetrics& hlo_op_metrics) {
  OpMetrics* tf_op_metrics = OpMetricsDbBuilder::LookupOrInsertNewOpMetrics(
  /*hlo_module_id=*/0, tf_op_name);
  - if (tf_op_metrics->category().empty())
  - tf_op_metrics->set_category(tf_op_type.data(), tf_op_type.size());
  + if (tf_op_metrics->category().empty()) {
  + tf_op_metrics->set_category(
  + tf_op_type == kUnknownOp ? "Unknown" : string(tf_op_type));
  + }
  // The occurrences of a TF-op is the maximum among the occurrences of all
  // HLO-ops that it contains.
  tf_op_metrics->set_occurrences(
  