Allow generation of a chromium outdirs when enable_extensions=false

extensions/components/native_app_window/BUILD.gn

Index: extensions/components/native_app_window/BUILD.gn
diff --git a/extensions/components/native_app_window/BUILD.gn b/extensions/components/native_app_window/BUILD.gn
index 5136e2a008b31350a92c748e3e91678d53ade7e8..f856c4ffe74ad4db9ef221ee253717bd01dc7c5e 100644
--- a/extensions/components/native_app_window/BUILD.gn
+++ b/extensions/components/native_app_window/BUILD.gn
@@ -2,6 +2,11 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//extensions/features/features.gni")
+
+assert(enable_extensions,
+       "Cannot depend on extensions because enable_extensions=false.")
+
 static_library("native_app_window") {
   sources = [
     "native_app_window_views.cc",