Bug 1835859 [wpt PR 40306] - webrtc wpt: restore mid extension locall…

…y in simulcast tests, a=testonly

Automatic update from web-platform-tests
webrtc wpt: restore mid extension locally in simulcast tests

which is mandatory to implement per
  https://datatracker.ietf.org/doc/html/rfc8853#section-5.5

BUG=chromium:1422258

Change-Id: Ic9118a4082748ba1ddce397810d31e282d5e005e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4573634
Commit-Queue: Philipp Hancke <phanckemicrosoft.com>
Reviewed-by: Harald Alvestrand <htachromium.org>
Cr-Commit-Position: refs/heads/main{#1150858}

--

wpt-commits: db1ac12ce7bb790ae98a1d03a22b54b55b2a93d2
wpt-pr: 40306

UltraBlame original commit: 766795c3b130f39da100168d4f36a7d68ac98c95

testing/web-platform/tests/webrtc/simulcast/simulcast.js

@@ -719,6 +719,87 @@ sdp
 ;
 if
 (
+localDescription
+)
+{
+const
+localVideoSection
+=
+SDPUtils
+.
+splitSections
+(
+localDescription
+.
+sdp
+)
+[
+1
+]
+;
+const
+localParameters
+=
+SDPUtils
+.
+parseRtpParameters
+(
+localVideoSection
+)
+;
+const
+localMidExtension
+=
+localParameters
+.
+headerExtensions
+.
+find
+(
+ext
+=
+>
+ext
+.
+uri
+=
+=
+=
+'
+urn
+:
+ietf
+:
+params
+:
+rtp
+-
+hdrext
+:
+sdes
+:
+mid
+'
+)
+;
+if
+(
+localMidExtension
+)
+{
+rtpParameters
+.
+headerExtensions
+.
+push
+(
+localMidExtension
+)
+;
+}
+}
+if
+(
 !
 rids
 )