在WebRTC代码中启用TRACE_EVENT

    bool WebRtcVideoChannel2::SetRtpSendParameters(
    uint32_t ssrc,
    const webrtc::RtpParameters& parameters) {
      TRACE_EVENT0("webrtc", "WebRtcVideoChannel2::SetRtpSendParameters");
      rtc::CritScope stream_lock(&stream_crit_);
      auto it = send_streams_.find(ssrc);
      if (it == send_streams_.end()) {
    LOG(LS_ERROR) << "Attempting to set RTP send parameters for stream "
                  << "with ssrc " << ssrc << " which doesn't exist.";
    return false;
      }
    
      // TODO(deadbeef): Handle setting parameters with a list of codecs in