text: #ifndef RTC_MESSAGESENDER_H_
  #define RTC_MESSAGESENDER_H_
  
  #include <string>
  #include "api/peer_connection_interface.h"
  
  class RTCMessageSender {
   public:
    virtual void onIceConnectionStateChange(
        webrtc::PeerConnectionInterface::IceConnectionState new_state) = 0;
    virtual void onIceCandidate(const std::string sdp_mid,
                                const int sdp_mlineindex,
                                const std::string sdp) = 0;
    virtual void onCreateDescription(webrtc::SdpType type,
                                     const std::string sdp) = 0;
    virtual void onSetDescription(webrtc::SdpType type) = 0;
  };
  
  #endif
  