Sends messages through Fleetspeak.

def _SendOp(self):
    """Sends messages through Fleetspeak."""
    msg = self._sender_queue.get()
    msgs = []
    background_msgs = []
    if not msg.require_fastpoll:
      background_msgs.append(msg)
    else:
      msgs.append(msg)

    count = 1
    size = len(msg.SerializeToString())

    while count < 100 and size < 1024 * 1024:
      try:
        msg = self._sender_queue.get(timeout=1)
        if not msg.require_fastpoll:
          background_msgs.append(msg)
        else:
          msgs.append(msg)
        count += 1
        size += len(msg.SerializeToString())
      except queue.Empty:
        break

    if msgs:
      self._SendMessages(msgs)
    if background_msgs:
      self._SendMessages(background_msgs, background=True)