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

Bug: webrtc:12338
Change-Id: Ia8a9adea291d594e4f59a6a1203a7bfb0758adac
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/227165
Commit-Queue: Artem Titov <titovartem@webrtc.org>
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#34684}
diff --git a/modules/video_coding/nack_requester.cc b/modules/video_coding/nack_requester.cc
index 6983576..dac85fc 100644
--- a/modules/video_coding/nack_requester.cc
+++ b/modules/video_coding/nack_requester.cc
@@ -195,7 +195,7 @@
     return 0;
   }
 
-  // Since the |newest_seq_num_| is a packet we have actually received we know
+  // Since the `newest_seq_num_` is a packet we have actually received we know
   // that packet has never been Nacked.
   if (seq_num == newest_seq_num_)
     return 0;