stop sending x-peer-id in peerconnection_server

the comment about why that is not a thing dates from 2013.

BUG=None

Change-Id: I97ec5090fc1acb4361bc8472fe605dafea89aa1d
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/183545
Reviewed-by: Tommi <tommi@webrtc.org>
Commit-Queue: Philipp Hancke <philipp.hancke@googlemail.com>
Cr-Commit-Position: refs/heads/master@{#32267}
diff --git a/examples/peerconnection/client/peer_connection_client.cc b/examples/peerconnection/client/peer_connection_client.cc
index b458927..9bf2a0f 100644
--- a/examples/peerconnection/client/peer_connection_client.cc
+++ b/examples/peerconnection/client/peer_connection_client.cc
@@ -465,8 +465,7 @@
 
   *peer_id = -1;
 
-  // See comment in peer_channel.cc for why we use the Pragma header and
-  // not e.g. "X-Peer-Id".
+  // See comment in peer_channel.cc for why we use the Pragma header.
   GetHeaderValue(response, *eoh, "\r\nPragma: ", peer_id);
 
   return true;