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/timestamp_map.cc b/modules/video_coding/timestamp_map.cc
index f6fb818..f843ea6 100644
--- a/modules/video_coding/timestamp_map.cc
+++ b/modules/video_coding/timestamp_map.cc
@@ -62,7 +62,7 @@
 }
 
 size_t VCMTimestampMap::Size() const {
-  // The maximum number of elements in the list is |capacity_| - 1. The list is
+  // The maximum number of elements in the list is `capacity_` - 1. The list is
   // empty if the add and pop indices are equal.
   return next_add_idx_ >= next_pop_idx_
              ? next_add_idx_ - next_pop_idx_