Use backticks not vertical bars to denote variables in comments

Bug: webrtc:12338
Change-Id: I89c8b3a328d04203177522cbdfd9e606fd4bce4c
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/228246
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Commit-Queue: Artem Titov <titovartem@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#34696}

sdk/android/api/org/webrtc/DataChannel.java

@@ -82,7 +82,7 @@ public class DataChannel {
     /** The data channel state has changed. */
     @CalledByNative("Observer") public void onStateChange();
     /**
-     * A data buffer was successfully received.  NOTE: |buffer.data| will be
+     * A data buffer was successfully received.  NOTE: `buffer.data` will be
      * freed once this function returns so callers who want to use the data
      * asynchronously must make sure to copy it first.
      */