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

Bug: webrtc:12338
Change-Id: I3db5820cbd4f2ccaa5bba308a4ba0bcb895ed9ad
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/226946
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Commit-Queue: Artem Titov <titovartem@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#34566}
diff --git a/common_video/frame_rate_estimator.h b/common_video/frame_rate_estimator.h
index 4cdd284..95219a5 100644
--- a/common_video/frame_rate_estimator.h
+++ b/common_video/frame_rate_estimator.h
@@ -43,7 +43,7 @@
   // Get the current average FPS, based on the frames currently in the window.
   absl::optional<double> GetAverageFps() const;
 
-  // Move the window so it ends at |now|, and return the new fps estimate.
+  // Move the window so it ends at `now`, and return the new fps estimate.
   absl::optional<double> GetAverageFps(Timestamp now);
 
   // Completely clear the averaging window.
diff --git a/common_video/h264/h264_bitstream_parser.cc b/common_video/h264/h264_bitstream_parser.cc
index 6eee02e..bc2104c 100644
--- a/common_video/h264/h264_bitstream_parser.cc
+++ b/common_video/h264/h264_bitstream_parser.cc
@@ -152,7 +152,7 @@
   // else
   {
     // ref_pic_list_modification():
-    // |slice_type| checks here don't use named constants as they aren't named
+    // `slice_type` checks here don't use named constants as they aren't named
     // in the spec for this segment. Keeping them consistent makes it easier to
     // verify that they are both the same.
     if (slice_type % 5 != 2 && slice_type % 5 != 4) {
diff --git a/common_video/h264/sps_vui_rewriter.h b/common_video/h264/sps_vui_rewriter.h
index 311db30..ef80d5b 100644
--- a/common_video/h264/sps_vui_rewriter.h
+++ b/common_video/h264/sps_vui_rewriter.h
@@ -50,7 +50,7 @@
       rtc::Buffer* destination,
       Direction Direction);
 
-  // Parses NAL units from |buffer|, strips AUD blocks and rewrites VUI in SPS
+  // Parses NAL units from `buffer`, strips AUD blocks and rewrites VUI in SPS
   // blocks if necessary.
   static rtc::Buffer ParseOutgoingBitstreamAndRewrite(
       rtc::ArrayView<const uint8_t> buffer,
diff --git a/common_video/include/video_frame_buffer_pool.h b/common_video/include/video_frame_buffer_pool.h
index 6af1175..539a6cc 100644
--- a/common_video/include/video_frame_buffer_pool.h
+++ b/common_video/include/video_frame_buffer_pool.h
@@ -40,7 +40,7 @@
   ~VideoFrameBufferPool();
 
   // Returns a buffer from the pool. If no suitable buffer exist in the pool
-  // and there are less than |max_number_of_buffers| pending, a buffer is
+  // and there are less than `max_number_of_buffers` pending, a buffer is
   // created. Returns null otherwise.
   rtc::scoped_refptr<I420Buffer> CreateI420Buffer(int width, int height);
   rtc::scoped_refptr<NV12Buffer> CreateNV12Buffer(int width, int height);
diff --git a/common_video/libyuv/include/webrtc_libyuv.h b/common_video/libyuv/include/webrtc_libyuv.h
index 03c9ff4..905219b 100644
--- a/common_video/libyuv/include/webrtc_libyuv.h
+++ b/common_video/libyuv/include/webrtc_libyuv.h
@@ -98,9 +98,9 @@
                 const I420BufferInterface& test_buffer);
 
 // Helper function for scaling NV12 to NV12.
-// If the |src_width| and |src_height| matches the |dst_width| and |dst_height|,
-// then |tmp_buffer| is not used. In other cases, the minimum size of
-// |tmp_buffer| should be:
+// If the `src_width` and `src_height` matches the `dst_width` and `dst_height`,
+// then `tmp_buffer` is not used. In other cases, the minimum size of
+// `tmp_buffer` should be:
 //   (src_width/2) * (src_height/2) * 2 + (dst_width/2) * (dst_height/2) * 2
 void NV12Scale(uint8_t* tmp_buffer,
                const uint8_t* src_y,