Add a usage pattern bit for host-host connections.

Bug: None
Change-Id: I66dee594295212fcc40a7706f688c9ab15967775
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/149341
Commit-Queue: Qingsi Wang <qingsi@webrtc.org>
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#29172}

pc/peer_connection.cc

@@ -4316,6 +4316,13 @@ void PeerConnection::OnSelectedCandidatePairChanged(
     return;
   }
 
+  if (event.selected_candidate_pair.local_candidate().type() ==
+          LOCAL_PORT_TYPE &&
+      event.selected_candidate_pair.remote_candidate().type() ==
+          LOCAL_PORT_TYPE) {
+    NoteUsageEvent(UsageEvent::DIRECT_CONNECTION_SELECTED);
+  }
+
   Observer()->OnIceSelectedCandidatePairChanged(event);
 }