message: Add workaround method for deprecated code.
  This is to allow downstream cases to be able to set the
  media_has_been_sent flag in the sender as it's being
  removed from RtpState.
  Cr-Commit-Position: refs/heads/master@{#31545}
diff: @@ -294,6 +294,10 @@ class ModuleRtpRtcpImpl : public RtpRtcp, public RTCPReceiver::ModuleRtpRtcp {
  RTCPReceiver* rtcp_receiver() { return &rtcp_receiver_; }
  const RTCPReceiver* rtcp_receiver() const { return &rtcp_receiver_; }
  + void SetMediaHasBeenSent(bool media_has_been_sent) {
  + rtp_sender_->packet_sender.SetMediaHasBeenSent(media_has_been_sent);
  + }
  +
  Clock* clock() const { return clock_; }
  // TODO(sprang): Remove when usage is gone.
  