Change transport sequence number extension strings to specify what revision is implemented.

BUG=webrtc:5610
R=mflodman@webrtc.org

Review URL: https://codereview.webrtc.org/1754653002 .

Cr-Commit-Position: refs/heads/master@{#11831}

webrtc/config.cc

diff --git a/webrtc/config.cc b/webrtc/config.cc
index e118a85..c8cb9ef 100644
--- a/webrtc/config.cc
+++ b/webrtc/config.cc
@@ -37,7 +37,7 @@
 const char* RtpExtension::kAudioLevel =
     "urn:ietf:params:rtp-hdrext:ssrc-audio-level";
 const char* RtpExtension::kTransportSequenceNumber =
-    "http://www.ietf.org/id/draft-holmer-rmcat-transport-wide-cc-extensions";
+    "http://www.ietf.org/id/draft-holmer-rmcat-transport-wide-cc-extensions-01";
 
 bool RtpExtension::IsSupportedForAudio(const std::string& name) {
   return name == webrtc::RtpExtension::kAbsSendTime ||