message: Removing redudancy in device mapping logging
diff: @@ -349,12 +349,12 @@ DirectSession::DirectSession(const SessionOptions& options,
  int devices_added = 0;
  if (options.config.log_device_placement()) {
  const string mapping_str = device_mgr_->DeviceMappingString();
  + string msg;
  if (mapping_str.empty()) {
  - printf("Device mapping: no known devices.\n");
  + msg = "Device mapping: no known devices.";
  } else {
  - printf("Device mapping:\n%s", mapping_str.c_str());
  + msg = strings::StrCat("Device mapping:\n", mapping_str);
  }
  - string msg = strings::StrCat("Device mapping:\n", mapping_str);
  if (!logging::LogToListeners(msg)) {
  LOG(INFO) << msg;
  }
  