Don't check is_ios in chrome/, it's always false there.

chrome/app/resources/BUILD.gn

 # Copyright 2014 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/chrome_build.gni")
 import("//chrome/common/features.gni")
 import("//tools/grit/grit_rule.gni")
 
+assert(!is_ios, "Chromium/iOS shouldn't use anything in //chrome")
+
 grit("locale_settings") {
   source = "locale_settings.grd"
   defines = chrome_grit_defines
   output_dir = "$root_gen_dir/chrome"
   outputs = [
     "grit/locale_settings.h",
     "locale_settings_am.pak",
     "locale_settings_ar.pak",
     "locale_settings_bg.pak",
     "locale_settings_bn.pak",
@@ skipping 46 matching lines @@
     "locale_settings_uk.pak",
     "locale_settings_vi.pak",
     "locale_settings_zh-CN.pak",
     "locale_settings_zh-TW.pak",
   ]
 }
 
 grit("platform_locale_settings") {
   if (is_win) {
     source = "locale_settings_win.grd"
-  } else if (is_mac || is_ios) {
+  } else if (is_mac) {
     source = "locale_settings_mac.grd"
   } else if (is_chromeos) {
     if (is_chrome_branded) {
       source = "locale_settings_google_chromeos.grd"
     } else {
       source = "locale_settings_chromiumos.grd"
     }
   } else if (is_posix) {
     # All other posix systems just use the Linux one.
     source = "locale_settings_linux.grd"
@@ skipping 53 matching lines @@
     "platform_locale_settings_th.pak",
     "platform_locale_settings_tr.pak",
     "platform_locale_settings_uk.pak",
     "platform_locale_settings_vi.pak",
     "platform_locale_settings_zh-CN.pak",
     "platform_locale_settings_zh-TW.pak",
   ]
 
   output_dir = "$root_gen_dir/chrome"
 }