Add initial prototype for the GN meta-buildsystem.

tools/gn/target_generator_unittest.cc

Index: tools/gn/target_generator_unittest.cc
diff --git a/chrome/test/data/chromeos/app_mode/kiosk_test_app/src/app_main.js b/tools/gn/target_generator_unittest.cc
similarity index 57%
copy from chrome/test/data/chromeos/app_mode/kiosk_test_app/src/app_main.js
copy to tools/gn/target_generator_unittest.cc
index 6201556e0cded45f5201db1cc0ca3f09f98a1080..feef6a96912e4ee6bfba691afbf5fa5a0bbffe77 100644
--- a/chrome/test/data/chromeos/app_mode/kiosk_test_app/src/app_main.js
+++ b/tools/gn/target_generator_unittest.cc
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-window.addEventListener('load', function onload() {
-  window.close();
-});
+#include "testing/gtest/include/gtest/gtest.h"
+#include "tools/gn/filesystem_utils.h"
+#include "tools/gn/target_generator.h"