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

Bug: webrtc:12338
Change-Id: I52eb3b6675c4705e22f51b70799ed6139a3b46bc
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/227164
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Commit-Queue: Artem Titov <titovartem@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#34686}

modules/rtp_rtcp/source/rtp_sender.cc

@@ -393,7 +393,7 @@ std::vector<std::unique_ptr<RtpPacketToSend>> RTPSender::GeneratePadding(
           packet_history_->GetPayloadPaddingPacket(
               [&](const RtpPacketToSend& packet)
                   -> std::unique_ptr<RtpPacketToSend> {
-                // Limit overshoot, generate <= |max_padding_size_factor_| *
+                // Limit overshoot, generate <= `max_padding_size_factor_` *
                 // target_size_bytes.
                 const size_t max_overshoot_bytes = static_cast<size_t>(
                     ((max_padding_size_factor_ - 1.0) * target_size_bytes) +
@@ -555,7 +555,7 @@ std::unique_ptr<RtpPacketToSend> RTPSender::AllocatePacket() const {
   // sender can reduce overhead by omitting these header extensions once it
   // knows that the receiver has "bound" the SSRC.
   // This optimization can be configured by setting
-  // |always_send_mid_and_rid_| appropriately.
+  // `always_send_mid_and_rid_` appropriately.
   //
   // The algorithm here is fairly simple: Always attach a MID and/or RID (if
   // configured) to the outgoing packets until an RTCP receiver report comes