message: Lower function def debug string to VLOG(4) (consistent with other appearance).
diff: @@ -724,8 +724,8 @@ Status ProcessFunctionLibraryRuntime::InstantiateMultiDevice(
  options.graph_collector->CollectOptimizedGraph(def);
  }
  - VLOG(2) << "Main function graph to be partitioned:";
  - VLOG(2) << DebugString(graph->ToGraphDefDebug());
  + VLOG(4) << "Main function graph to be partitioned:";
  + VLOG(4) << DebugString(graph->ToGraphDefDebug());
  std::unordered_map<string, std::unique_ptr<Graph>> subgraphs;
  TF_RETURN_IF_ERROR(
  