DCHECK that the red payload type doesn't have invalid values when FEC is enabled.

webrtc/modules/rtp_rtcp/source/rtp_sender_video.cc

 /*
  *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 151 matching lines @@
                       << next_fec_sequence_number;
     }
     delete fec_packet;
     ++next_fec_sequence_number;
   }
 }
 
 void RTPSenderVideo::SetGenericFECStatus(const bool enable,
                                          const uint8_t payloadTypeRED,
                                          const uint8_t payloadTypeFEC) {
+  RTC_DCHECK(!enable || payloadTypeRED > 0);
   rtc::CritScope cs(&crit_);
   fec_enabled_ = enable;
   red_payload_type_ = payloadTypeRED;
   fec_payload_type_ = payloadTypeFEC;
   memset(&delta_fec_params_, 0, sizeof(delta_fec_params_));
   memset(&key_fec_params_, 0, sizeof(key_fec_params_));
   delta_fec_params_.max_fec_frames = key_fec_params_.max_fec_frames = 1;
   delta_fec_params_.fec_mask_type = key_fec_params_.fec_mask_type =
       kFecMaskRandom;
 }
@@ skipping 170 matching lines @@
   rtc::CritScope cs(&crit_);
   return _retransmissionSettings;
 }
 
 void RTPSenderVideo::SetSelectiveRetransmissions(uint8_t settings) {
   rtc::CritScope cs(&crit_);
   _retransmissionSettings = settings;
 }
 
 }  // namespace webrtc