Enable GN check on //net.

This should avoid the situation where WebRTC's GN check is green and
Chromium (which turns it ON for //third_party/webrtc) fails.

Bug: webrtc:12614
Change-Id: Id4c06ac57e9faa07c5e43491a61fbc093c68a40d
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/217221
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Florent Castelli <orphis@webrtc.org>
Reviewed-by: Victor Boivie <boivie@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#33900}
diff --git a/.gn b/.gn
index 9c43afd..08f9da91 100644
--- a/.gn
+++ b/.gn
@@ -35,6 +35,7 @@
   "//logging/*",
   "//media/*",
   "//modules/*",
+  "//net/*",
   "//p2p/*",
   "//pc/*",
   "//rtc_base/*",