Frame marking RTP header extension (PART 1: implement extension)

Bug: webrtc:7765
Change-Id: I23896d121afd6be4bce5ff4deaf736149efebcdb
Reviewed-on: https://webrtc-review.googlesource.com/85200
Commit-Queue: Danil Chapovalov <danilchap@webrtc.org>
Reviewed-by: Stefan Holmer <stefan@webrtc.org>
Reviewed-by: Sergey Silkin <ssilkin@webrtc.org>
Reviewed-by: Danil Chapovalov <danilchap@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#24695}
diff --git a/api/rtpparameters.cc b/api/rtpparameters.cc
index 62ca3fc..9beae82 100644
--- a/api/rtpparameters.cc
+++ b/api/rtpparameters.cc
@@ -129,6 +129,10 @@
 const char RtpExtension::kMidUri[] = "urn:ietf:params:rtp-hdrext:sdes:mid";
 const int RtpExtension::kMidDefaultId = 9;
 
+const char RtpExtension::kFrameMarkingUri[] =
+    "http://tools.ietf.org/html/draft-ietf-avtext-framemarking-07";
+const int RtpExtension::kFrameMarkingDefaultId = 10;
+
 const char RtpExtension::kEncryptHeaderExtensionsUri[] =
     "urn:ietf:params:rtp-hdrext:encrypt";
 
@@ -149,7 +153,8 @@
          uri == webrtc::RtpExtension::kPlayoutDelayUri ||
          uri == webrtc::RtpExtension::kVideoContentTypeUri ||
          uri == webrtc::RtpExtension::kVideoTimingUri ||
-         uri == webrtc::RtpExtension::kMidUri;
+         uri == webrtc::RtpExtension::kMidUri ||
+         uri == webrtc::RtpExtension::kFrameMarkingUri;
 }
 
 bool RtpExtension::IsEncryptionSupported(const std::string& uri) {