Implement FrameMarking header extension support

webrtc/modules/rtp_rtcp/source/rtp_header_extensions.h

 /*
  *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 #ifndef WEBRTC_MODULES_RTP_RTCP_SOURCE_RTP_HEADER_EXTENSIONS_H_
@@ skipping 164 matching lines @@
   static constexpr const char kUri[] =
       "urn:ietf:params:rtp-hdrext:sdes:repaired-rtp-stream-id";
 };
 
 class RtpMid : public BaseRtpStringExtension {
  public:
   static constexpr RTPExtensionType kId = kRtpExtensionMid;
   static constexpr const char kUri[] = "urn:ietf:params:rtp-hdrext:sdes:mid";
 };
 
+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_