Implement FrameMarking header extension support

webrtc/modules/rtp_rtcp/source/rtp_header_extensions.h

Index: webrtc/modules/rtp_rtcp/source/rtp_header_extensions.h
diff --git a/webrtc/modules/rtp_rtcp/source/rtp_header_extensions.h b/webrtc/modules/rtp_rtcp/source/rtp_header_extensions.h
index d3e72ebd22af9b294d04daa432d5f14e40ad57f4..ac341b746f40b85ff22437766103cff6a7adf521 100644
--- a/webrtc/modules/rtp_rtcp/source/rtp_header_extensions.h
+++ b/webrtc/modules/rtp_rtcp/source/rtp_header_extensions.h
@@ -156,5 +156,15 @@ class RepairedRtpStreamId {
   static bool Write(uint8_t* data, const std::string& rsid);
 };
 
+class FrameMarking {
+ public:
+  static constexpr RTPExtensionType kId = kRtpExtensionFrameMarking;
+  static constexpr const char* kUri = "urn:ietf:params:rtp-hdrext:framemarking";
+  static bool Parse(rtc::ArrayView<const uint8_t> data,
+                    FrameMarks* frame_marks);
+  static size_t ValueSize(const FrameMarks& frame_marks);
+  static bool Write(uint8_t* data, const FrameMarks& frame_marks);
+};
+
 }  // namespace webrtc
 #endif  // WEBRTC_MODULES_RTP_RTCP_SOURCE_RTP_HEADER_EXTENSIONS_H_