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/video/video_source_interface.h b/api/video/video_source_interface.h
index 8b5823f..d66a235 100644
--- a/api/video/video_source_interface.h
+++ b/api/video/video_source_interface.h
@@ -54,7 +54,7 @@
   int max_framerate_fps = std::numeric_limits<int>::max();
 
   // Tells the source that the sink wants width and height of the video frames
-  // to be divisible by |resolution_alignment|.
+  // to be divisible by `resolution_alignment`.
   // For example: With I420, this value would be a multiple of 2.
   // Note that this field is unrelated to any horizontal or vertical stride
   // requirements the encoder has on the incoming video frame buffers.
@@ -71,13 +71,13 @@
   // to scaleResolutionDownBy or turning off simulcast or SVC layers.
   //
   // For example, we may capture at 720p and due to adaptation (e.g. applying
-  // |max_pixel_count| constraints) create webrtc::VideoFrames of size 480p, but
+  // `max_pixel_count` constraints) create webrtc::VideoFrames of size 480p, but
   // if we do scaleResolutionDownBy:2 then the only resolution we end up
   // encoding is 240p. In this case we still need to provide webrtc::VideoFrames
   // of size 480p but we can optimize internal buffers for 240p, avoiding
   // downsampling to 480p if possible.
   //
-  // Note that the |resolutions| can change while frames are in flight and
+  // Note that the `resolutions` can change while frames are in flight and
   // should only be used as a hint when constructing the webrtc::VideoFrame.
   std::vector<FrameSize> resolutions;
 };