Reland of 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..8eaac7462aacf8d824cf264399bfabbf3a73aa18 100644
--- a/webrtc/modules/video_coding/include/video_coding_defines.h
+++ b/webrtc/modules/video_coding/include/video_coding_defines.h
@@ -61,8 +61,17 @@ struct VCMFrameCount {
 // rendered.
 class VCMReceiveCallback {
  public:
+  // TODO(ilnik): Once deprecation is complete, change this to pure virtual.
   virtual int32_t FrameToRender(VideoFrame& videoFrame,  // NOLINT
-                                rtc::Optional<uint8_t> qp) = 0;
+                                rtc::Optional<uint8_t> qp,
+                                VideoContentType /*content_type*/) {
+    return FrameToRender(videoFrame, qp);
+  }
+  // DEPRECATED. Use the other overloaded version.
+  virtual int32_t FrameToRender(VideoFrame& videoFrame,  // NOLINT
+                                rtc::Optional<uint8_t> qp) {
+    return -1;
+  }
   virtual int32_t ReceivedDecodedReferenceFrame(const uint64_t pictureId) {
     return -1;
   }