message: Add a log message.
  I observed this "no id" log in the bug report on b/260957808#comment1.
  I think the log is not related to b/260957808, but just in case.
diff: @@ -494,7 +494,7 @@ void SessionUsageObserver::EvalCommandHandler(
  if (IsSessionIndependentCommand(input.type())) {
  return;
  } else if (!input.has_id()) {
  - LOG(WARNING) << "no id";
  + LOG(WARNING) << "no id. input type: " << input.type();
  // Should have id
  return;
  }
  