message: Use total_node_costs in VirtualScheduler op_costs_.
diff: @@ -769,7 +769,7 @@ bool VirtualScheduler::MarkCurrNodeExecuted(const Costs& node_costs) {
  string node_description = GetOpDescription(op_context.op_info);
  op_counts_[node_description] += 1;
  op_costs_[node_description] =
  - std::make_pair(node_costs.execution_time.asMicroSeconds().count(),
  + std::make_pair(total_node_costs.execution_time.asMicroSeconds().count(),
  !node_costs.inaccurate);
  }
  