diff --git a/tools/gn/args.cc b/tools/gn/args.cc
index 800996b..0dcceec 100644
--- a/tools/gn/args.cc
+++ b/tools/gn/args.cc
@@ -307,6 +307,8 @@
 #else
   #error Unknown OS type.
 #endif
+  // NOTE: Adding a new port? Please follow
+  // https://chromium.googlesource.com/chromium/src/+/master/docs/new_port_policy.md
 
   // Host architecture.
   static const char kX86[] = "x86";