Rename is_chromeos in chrome/src.

chrome/common/variations/BUILD.gn

Index: chrome/common/variations/BUILD.gn
diff --git a/chrome/common/variations/BUILD.gn b/chrome/common/variations/BUILD.gn
index 8a539761949457dc67e25d1608a323041ae92629..4f616bf44019747d10b8e9e0daaf109768270dc0 100644
--- a/chrome/common/variations/BUILD.gn
+++ b/chrome/common/variations/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")
+
 action("fieldtrial_testing_config_action") {
   visibility = [ ":fieldtrial_testing_config" ]
   script = "//tools/variations/fieldtrial_to_struct.py"
@@ -15,7 +17,7 @@ action("fieldtrial_testing_config_action") {
   if (is_linux) {
     source = "//testing/variations/fieldtrial_testing_config_linux.json"
   }
-  if (is_chromeos) {
+  if (use_cros_fe) {
     source = "//testing/variations/fieldtrial_testing_config_chromeos.json"
   }
   if (is_android) {