Rename is_chromeos in chrome/src.

components/signin/core/browser/BUILD.gn

Index: components/signin/core/browser/BUILD.gn
diff --git a/components/signin/core/browser/BUILD.gn b/components/signin/core/browser/BUILD.gn
index a7d469470df7ede24cadc3646bda5adaa7bf0c8b..9d2aa36763a512bd8f743e754fe0cf71f491ee59 100644
--- a/components/signin/core/browser/BUILD.gn
+++ b/components/signin/core/browser/BUILD.gn
@@ -2,6 +2,8 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/features.gni")
+
 static_library("browser") {
   sources = [
     "about_signin_internals.cc",
@@ -76,7 +78,7 @@ static_library("browser") {
     "//components/webdata/common",
   ]
 
-  if (is_chromeos) {
+  if (use_cros_fe) {
     sources -= [ "signin_manager.cc" ]
   }