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 c0a4bca913e6ce96a1ceaf0098fbb8b34d447e9a..296e553bc16cc8bd3ccd530e611d0750f5bbb502 100644
--- a/webrtc/modules/rtp_rtcp/source/rtp_header_extensions.h
+++ b/webrtc/modules/rtp_rtcp/source/rtp_header_extensions.h
@@ -175,5 +175,20 @@ 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);
+
+  static uint8_t CreateLayerId(const RTPVideoHeaderVP9& vp9);
+
+ private:
+  static bool IsScalable(const FrameMarks& frame_marks);
+};
+
 }  // namespace webrtc
 #endif  // WEBRTC_MODULES_RTP_RTCP_SOURCE_RTP_HEADER_EXTENSIONS_H_