Internal built-in module code should be wrapped under api namespace.

browser/api/atom_api_window.cc

@@ -0,0 +1,15 @@
+// Copyright (c) 2013 GitHub, Inc. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "browser/api/atom_api_window.h"
+
+namespace atom {
+
+static void Initialize(v8::Handle<v8::Object> target) {
+  target->Set(v8::String::New("hello"), v8::String::New("world"));
+}
+
+}  // namespace atom
+
+NODE_MODULE(atom_api_window, atom::Initialize)