Use backticks not vertical bars to denote variables in comments for /api

Bug: webrtc:12338
Change-Id: Ib97b2c3d64dbd895f261ffa76a2e885bd934a87f
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/226940
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Commit-Queue: Artem Titov <titovartem@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#34554}
diff --git a/api/stats_types.cc b/api/stats_types.cc
index 6fdc7e8..6e62bba7 100644
--- a/api/stats_types.cc
+++ b/api/stats_types.cc
@@ -835,7 +835,7 @@
   return InsertNew(id);
 }
 
-// Looks for a report with the given |id|.  If one is not found, null
+// Looks for a report with the given `id`.  If one is not found, null
 // will be returned.
 StatsReport* StatsCollection::Find(const StatsReport::Id& id) {
   RTC_DCHECK(thread_checker_.IsCurrent());