Rename is_chromeos in chrome/src.

extensions/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.
 
 # TODO(rockot) bug 505926: Don't include chrome files from here.
 # See chrome_browser_tests_extensions_sources below
 import("//chrome/chrome_tests.gni")
 import("//extensions/extensions.gni")
 import("//testing/test.gni")
 import("//tools/grit/grit_rule.gni")
@@ skipping 183 matching lines @@
     "//third_party/mojo/src/mojo/edk/system",
     "//third_party/mojo/src/mojo/public/cpp/bindings",
   ]
 
   data_deps = [ "//third_party/mesa:osmesa" ]
 
   if (is_win) {
     deps += [ "//base/allocator" ]
   }
 
-  if (is_chromeos) {
+  if (use_cros_fe) {
     sources += [
       # TODO(rockot): There are two implementations of VpnServiceFactory, a
       # stub in app_shell and a real one in Chrome. This is wrong.
       "shell/browser/api/vpn_provider/vpn_service_factory.cc",
     ]
 
     deps += [ "//chromeos:test_support" ]
   }
 }
 
@@ skipping 165 matching lines @@
     "//testing/gtest",
     "//third_party/hunspell",
     "//third_party/icu",
     "//third_party/libpng",
     "//third_party/zlib",
     "//ui/base:test_support",
     "//ui/resources:ui_test_pak",
     "//ui/web_dialogs:test_support",
   ]
 }