Fix issues with RestartingSendStreamPreservesRtpStatesWithRtx

webrtc/modules/rtp_rtcp/source/rtp_sender_video.cc

Index: webrtc/modules/rtp_rtcp/source/rtp_sender_video.cc
diff --git a/webrtc/modules/rtp_rtcp/source/rtp_sender_video.cc b/webrtc/modules/rtp_rtcp/source/rtp_sender_video.cc
index 9757e52e80b6545ed159150d615501e15b04ffc0..5364a9b831d57002bb49e6b2aa5d7fa9a39b33d2 100644
--- a/webrtc/modules/rtp_rtcp/source/rtp_sender_video.cc
+++ b/webrtc/modules/rtp_rtcp/source/rtp_sender_video.cc
@@ -266,8 +266,10 @@ int32_t RTPSenderVideo::SendVideo(RtpVideoCodecTypes video_type,
     }
 
     // Write RTP header.
-    rtp_sender_->BuildRtpHeader(dataBuffer, payload_type, last,
-                                capture_timestamp, capture_time_ms);
+    int32_t header_length = rtp_sender_->BuildRtpHeader(
+        dataBuffer, payload_type, last, capture_timestamp, capture_time_ms);
+    if (header_length <= 0)
+      return -1;
 
     // According to
     // http://www.etsi.org/deliver/etsi_ts/126100_126199/126114/12.07.00_60/