Method deliver

example/cpp11/chat/chat_server.cpp:90–98

  }

  void deliver(const chat_message& msg)
  {
    bool write_in_progress = !write_msgs_.empty();
    write_msgs_.push_back(msg);
    if (!write_in_progress)
    {
      do_write();
    }
  }

private:
  void do_read_header()