Don't crash on unexpected stap-a or fu-a.

webrtc/modules/rtp_rtcp/source/rtp_format_h264.cc

Index: webrtc/modules/rtp_rtcp/source/rtp_format_h264.cc
diff --git a/webrtc/modules/rtp_rtcp/source/rtp_format_h264.cc b/webrtc/modules/rtp_rtcp/source/rtp_format_h264.cc
index 81dcb8b9e242b15bef9d7608f2d6b5a5971e3199..27479458315de126fa3e551128a748b618a81714 100644
--- a/webrtc/modules/rtp_rtcp/source/rtp_format_h264.cc
+++ b/webrtc/modules/rtp_rtcp/source/rtp_format_h264.cc
@@ -529,7 +529,8 @@ bool RtpDepacketizerH264::ProcessStapAOrSingleNalu(
         break;
       case H264::NaluType::kStapA:
       case H264::NaluType::kFuA:
-        RTC_NOTREACHED();
+        LOG(LS_WARNING) << "Unexpected STAP-A or FU-A received.";
+        return false;
     }
     RTPVideoHeaderH264* h264 = &parsed_payload->type.Video.codecHeader.H264;
     if (h264->nalus_length == kMaxNalusPerPacket) {