Reland of Add content type information to encoded images and corresponding rtp extension header

webrtc/modules/rtp_rtcp/source/rtp_rtcp_impl_unittest.cc

Index: webrtc/modules/rtp_rtcp/source/rtp_rtcp_impl_unittest.cc
diff --git a/webrtc/modules/rtp_rtcp/source/rtp_rtcp_impl_unittest.cc b/webrtc/modules/rtp_rtcp/source/rtp_rtcp_impl_unittest.cc
index 66ee51f7cfab6b96136faf299588da6eda2103a9..75e2dc17d1e51be6f6fb715905003b4a6a886beb 100644
--- a/webrtc/modules/rtp_rtcp/source/rtp_rtcp_impl_unittest.cc
+++ b/webrtc/modules/rtp_rtcp/source/rtp_rtcp_impl_unittest.cc
@@ -203,6 +203,7 @@
     rtp_video_header.width = codec_.width;
     rtp_video_header.height = codec_.height;
     rtp_video_header.rotation = kVideoRotation_0;
+    rtp_video_header.content_type = VideoContentType::UNSPECIFIED;
     rtp_video_header.playout_delay = {-1, -1};
     rtp_video_header.is_first_packet_in_frame = true;
     rtp_video_header.simulcastIdx = 0;