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

chrome/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/buildflag_header.gni")
 import("//build/config/chrome_build.gni")
 import("//build/config/compiler/compiler.gni")
 import("//build/config/compiler/pgo/pgo.gni")
 import("//build/config/features.gni")
 import("//build/config/locales.gni")
@@ skipping 18 matching lines @@
   import("//build/compiled_action.gni")
   import("//build/config/mac/rules.gni")
   import("//build/config/mac/symbols.gni")
   import("//build/mac/tweak_info_plist.gni")
   import("//build/util/branding.gni")
   import("//build/util/version.gni")
   import("//media/cdm/ppapi/cdm_paths.gni")
   import("//third_party/icu/config.gni")
 }
 
+assert(!is_ios, "Chromium/iOS shouldn't use anything in //chrome")
+
 if (enable_resource_whitelist_generation) {
   chrome_resource_whitelist = "$target_gen_dir/chrome_resource_whitelist.txt"
 }
 
 if (is_win) {
   action("reorder_imports") {
     script = "//build/win/reorder-imports.py"
 
     # See comment in chrome_dll.gypi in the hardlink_to_output
     # target for why this cannot be 'initial' like the DLL.
@@ skipping 1359 matching lines @@
     "//chrome/browser/resources:invalidations_resources",
     "//chrome/browser/resources:net_internals_resources",
     "//chrome/browser/resources:password_manager_internals_resources",
     "//chrome/browser/resources:policy_resources",
     "//chrome/browser/resources:quota_internals_resources",
     "//chrome/browser/resources:task_scheduler_internals_resources",
     "//chrome/browser/resources:translate_internals_resources",
     "//chrome/browser/resources:webapks_ui_resources",
   ]
 
-  if (!is_android && !is_ios) {
+  if (!is_android) {
     public_deps += [
       "//chrome/browser/resources:component_extension_resources",
       "//chrome/browser/resources:options_resources",
       "//chrome/browser/resources:settings_resources",
     ]
   }
 
   if (is_chromeos) {
     public_deps += [ "//chrome/browser/resources/chromeos/chromevox" ]
     public_deps += [ "//chrome/browser/resources/chromeos/select_to_speak" ]
@@ skipping 252 matching lines @@
       "//chrome/app/theme/$branding_path_component/product_logo_48.png",
       "//chrome/tools/build/linux/chrome-wrapper",
       "//third_party/xdg-utils/scripts/xdg-mime",
       "//third_party/xdg-utils/scripts/xdg-settings",
     ]
     outputs = [
       "$root_out_dir/{{source_file_part}}",
     ]
   }
 }