Reland "Use backticks not vertical bars to denote variables in comments for /pc"

Original change's description:
> Revert "Use backticks not vertical bars to denote variables in comments for /pc"
>
> This reverts commit 37ee0f5e594dd772ec6d620b5e5ea8a751b684f0.
>
> Reason for revert: Revert in order to be able to revert https://webrtc-review.googlesource.com/c/src/+/225642
>
> Original change's description:
> > Use backticks not vertical bars to denote variables in comments for /pc
> >
> > Bug: webrtc:12338
> > Change-Id: I88cf10afa5fc810b95d2a585ab2e895dcc163b63
> > Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/226953
> > Reviewed-by: Harald Alvestrand <hta@webrtc.org>
> > Commit-Queue: Artem Titov <titovartem@webrtc.org>
> > Cr-Commit-Position: refs/heads/master@{#34575}
>
> TBR=hta@webrtc.org,titovartem@webrtc.org,webrtc-scoped@luci-project-accounts.iam.gserviceaccount.com
>
> Change-Id: I5eddd3a14e1f664bf831e5c294fbc4de5f6a88af
> No-Presubmit: true
> No-Tree-Checks: true
> No-Try: true
> Bug: webrtc:12338
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/227082
> Reviewed-by: Björn Terelius <terelius@webrtc.org>
> Commit-Queue: Björn Terelius <terelius@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#34577}

Bug: webrtc:12338
Change-Id: I96bd229b73613c162d11d75fa4f5934e1b4295c7
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/227087
Commit-Queue: Artem Titov <titovartem@webrtc.org>
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#34611}
diff --git a/pc/peer_connection.cc b/pc/peer_connection.cc
index 8ddf42c..5bcd940 100644
--- a/pc/peer_connection.cc
+++ b/pc/peer_connection.cc
@@ -276,7 +276,7 @@
   bool default_enabled =
       (dependencies.cert_generator || !configuration.certificates.empty());
 
-  // The |configuration| can override the default value.
+  // The `configuration` can override the default value.
   return configuration.enable_dtls_srtp.value_or(default_enabled);
 }
 
@@ -499,7 +499,7 @@
       call_ptr_(call_.get()),
       // RFC 3264: The numeric value of the session id and version in the
       // o line MUST be representable with a "64 bit signed integer".
-      // Due to this constraint session id |session_id_| is max limited to
+      // Due to this constraint session id `session_id_` is max limited to
       // LLONG_MAX.
       session_id_(rtc::ToString(rtc::CreateRandomId64() & LLONG_MAX)),
       dtls_enabled_(dtls_enabled),
@@ -1195,7 +1195,7 @@
         break;
     }
   }
-  // If there is no |internal_sender| then |selector| is either null or does not
+  // If there is no `internal_sender` then `selector` is either null or does not
   // belong to the PeerConnection (in Plan B, senders can be removed from the
   // PeerConnection). This means that "all the stats objects representing the
   // selector" is an empty set. Invoking GetStatsReport() with a null selector
@@ -1225,7 +1225,7 @@
         break;
     }
   }
-  // If there is no |internal_receiver| then |selector| is either null or does
+  // If there is no `internal_receiver` then `selector` is either null or does
   // not belong to the PeerConnection (in Plan B, receivers can be removed from
   // the PeerConnection). This means that "all the stats objects representing
   // the selector" is an empty set. Invoking GetStatsReport() with a null
@@ -2418,7 +2418,7 @@
 
 void PeerConnection::TeardownDataChannelTransport_n() {
   if (sctp_mid_n_) {
-    // |sctp_mid_| may still be active through an SCTP transport.  If not, unset
+    // `sctp_mid_` may still be active through an SCTP transport.  If not, unset
     // it.
     RTC_LOG(LS_INFO) << "Tearing down data channel transport for mid="
                      << *sctp_mid_n_;