Bug 1843113 - Vendor libwebrtc from a624ee1be7

Upstream commit: https://webrtc.googlesource.com/src/+/a624ee1be7a11e795a849edb2a27dc1137d2b63d
    [M114] Avoid touching channel after OnSctpDataChannelClosed

    (cherry picked from commit eec1810760ccbdf95c68ed0d2c2ae10a8575551a)

    Bug: chromium:1454086
    Change-Id: I39573b706c4031d091c45a182b13cb3b2dba6233
    Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/309920
    Reviewed-by: Harald Alvestrand <hta@webrtc.org>
    Commit-Queue: Tomas Gunnarsson <tommi@webrtc.org>
    Cr-Original-Commit-Position: refs/heads/main@{#40332}
    Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/310922
    Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
    Cr-Commit-Position: refs/branch-heads/5735@{#5}
    Cr-Branched-From: df7df199abd619e75b9f1d9a7e12fc3f3f748775-refs/heads/main@{#39949}

third_party/libwebrtc/README.moz-ff-commit

@@ -23502,3 +23502,6 @@ e46e37b6f8
 # MOZ_LIBWEBRTC_SRC=/home/mfroman/mozilla/elm/.moz-fast-forward/moz-libwebrtc MOZ_LIBWEBRTC_BRANCH=mozpatches bash dom/media/webrtc/third_party_build/fast-forward-libwebrtc.sh
 # base of lastest vendoring
 d20849d071
+# MOZ_LIBWEBRTC_SRC=/home/mfroman/mozilla/elm/.moz-fast-forward/moz-libwebrtc MOZ_LIBWEBRTC_BRANCH=mozpatches bash dom/media/webrtc/third_party_build/fast-forward-libwebrtc.sh
+# base of lastest vendoring
+a624ee1be7

third_party/libwebrtc/README.mozilla

@@ -15690,3 +15690,5 @@ libwebrtc updated from /home/mfroman/mozilla/elm/.moz-fast-forward/moz-libwebrtc
 libwebrtc updated from /home/mfroman/mozilla/elm/.moz-fast-forward/moz-libwebrtc commit mozpatches on 2023-07-14T21:01:04.634768.
 # ./mach python dom/media/webrtc/third_party_build/vendor-libwebrtc.py --from-local /home/mfroman/mozilla/elm/.moz-fast-forward/moz-libwebrtc --commit mozpatches libwebrtc
 libwebrtc updated from /home/mfroman/mozilla/elm/.moz-fast-forward/moz-libwebrtc commit mozpatches on 2023-07-14T21:02:05.862286.
+# ./mach python dom/media/webrtc/third_party_build/vendor-libwebrtc.py --from-local /home/mfroman/mozilla/elm/.moz-fast-forward/moz-libwebrtc --commit mozpatches libwebrtc
+libwebrtc updated from /home/mfroman/mozilla/elm/.moz-fast-forward/moz-libwebrtc commit mozpatches on 2023-07-14T21:03:04.820705.

third_party/libwebrtc/pc/data_channel_controller.cc

@@ -77,12 +77,16 @@ void DataChannelController::OnChannelStateChanged(
     SctpDataChannel* channel,
     DataChannelInterface::DataState state) {
   RTC_DCHECK_RUN_ON(network_thread());
+
+  // Stash away the internal id here in case `OnSctpDataChannelClosed` ends up
+  // releasing the last reference to the channel.
+  const int channel_id = channel->internal_id();
+
   if (state == DataChannelInterface::DataState::kClosed)
     OnSctpDataChannelClosed(channel);
 
   signaling_thread()->PostTask(
-      SafeTask(signaling_safety_.flag(),
-               [this, channel_id = channel->internal_id(), state = state] {
+      SafeTask(signaling_safety_.flag(), [this, channel_id, state = state] {
                  pc_->OnSctpDataChannelStateChanged(channel_id, state);
                }));
 }