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

webrtc/modules/video_coding/include/video_coding_defines.h

Index: webrtc/modules/video_coding/include/video_coding_defines.h
diff --git a/webrtc/modules/video_coding/include/video_coding_defines.h b/webrtc/modules/video_coding/include/video_coding_defines.h
index 4ed80a6f81a1ad03b77ee25cc0364440a47a181f..3ae9981d9cda6530d1c42cc09965ee082d3dcc41 100644
--- a/webrtc/modules/video_coding/include/video_coding_defines.h
+++ b/webrtc/modules/video_coding/include/video_coding_defines.h
@@ -62,7 +62,8 @@ struct VCMFrameCount {
 class VCMReceiveCallback {
  public:
   virtual int32_t FrameToRender(VideoFrame& videoFrame,  // NOLINT
-                                rtc::Optional<uint8_t> qp) = 0;
+                                rtc::Optional<uint8_t> qp,
+                                VideoContentType content_type) = 0;
   virtual int32_t ReceivedDecodedReferenceFrame(const uint64_t pictureId) {
     return -1;
   }