[Chromecast] Require chromecast OWNERS to be aware of locale changes.

chromecast/app/BUILD.gn

 # Copyright 2015 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/locales.gni")
 import("//testing/test.gni")
 import("//tools/grit/grit_rule.gni")
 
 source_set("app") {
   sources = [
@@ skipping 94 matching lines @@
 grit("chromecast_settings") {
   source = "//chromecast/app/resources/chromecast_settings.grd"
   resource_ids = "//chromecast/app/resources/resource_ids"
 
   outputs = [
     "grit/chromecast_settings.h",
   ]
   foreach(locale, locales_with_fake_bidi) {
     outputs += [ "chromecast_settings_${locale}.pak" ]
   }
+
+  deps = [
+    ":verify_cast_locales",
+  ]
 }
+
+# This target ensures that Chromecast developers are notified when locales
+# change. If this target is breaking the build, the CAST_LOCALES list in
+# //chromecast/app/verify_cast_locales.py must be updated to match
+# |locales_with_fake_bidi|. Please see that file for more details. This action
+# will be run on fresh builds, and whenever |locales_with_fake_bidi| is updated.
+action("verify_cast_locales") {
+  script = "//chromecast/app/verify_cast_locales.py"
+
+  # This file will be stamped on success, preventing an unnecessary rebuild.
+  stamp_file = "$target_gen_dir/cast_locales_verified"
+  args = [
+    "-s",
+    rebase_path(stamp_file, "$root_out_dir"),
+  ]
+
+  args += locales_with_fake_bidi
+
+  outputs = [
+    stamp_file,
+  ]
+}