Remove faulty DCHECK in rtcp::TransportFeedback DecodeSymbol

webrtc/modules/rtp_rtcp/source/rtcp_packet/transport_feedback.cc

Index: webrtc/modules/rtp_rtcp/source/rtcp_packet/transport_feedback.cc
diff --git a/webrtc/modules/rtp_rtcp/source/rtcp_packet/transport_feedback.cc b/webrtc/modules/rtp_rtcp/source/rtcp_packet/transport_feedback.cc
index cce0075adef1cb8d56308861f7f0327896ed4676..a4f0f6bbdc56a50a25da45e955b9a1bde5cf589a 100644
--- a/webrtc/modules/rtp_rtcp/source/rtcp_packet/transport_feedback.cc
+++ b/webrtc/modules/rtp_rtcp/source/rtcp_packet/transport_feedback.cc
@@ -60,7 +60,11 @@ TransportFeedback::StatusSymbol DecodeSymbol(uint8_t value) {
       return TransportFeedback::StatusSymbol::kReceivedSmallDelta;
     case 2:
       return TransportFeedback::StatusSymbol::kReceivedLargeDelta;
+    case 3:
+      // It is invalid, but |value| comes from network, so can be any.
+      return TransportFeedback::StatusSymbol::kNotReceived;
     default:
+      // Caller should pass 2 bits max.
       RTC_NOTREACHED();
       return TransportFeedback::StatusSymbol::kNotReceived;
   }