Rename is_chromeos in chrome/src.

ui/views_content_client/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/ui.gni")
 
 component("views_content_client") {
   testonly = true
   sources = [
     "views_content_browser_client.cc",
@@ skipping 26 matching lines @@
     "//ui/views:test_support",
     "//ui/wm",
   ]
 
   if (use_aura) {
     sources += [
       "views_content_client_main_parts_aura.cc",
       "views_content_client_main_parts_aura.h",
     ]
 
-    if (!is_chromeos) {
+    if (!use_cros_fe) {
       sources += [ "views_content_client_main_parts_desktop_aura.cc" ]
     }
 
     deps += [ "//ui/aura" ]
   }
 
-  if (is_chromeos) {
+  if (use_cros_fe) {
     deps += [
       "//ui/aura:test_support",
       "//ui/wm:test_support",
     ]
   }
 }