Rename is_chromeos in chrome/src.

media/cast/BUILD.gn

Index: media/cast/BUILD.gn
diff --git a/media/cast/BUILD.gn b/media/cast/BUILD.gn
index b633d997d318c8de13bb37aee9ca67d249515d67..6d358cbc20bb456c1afe8391933a9e9460fc0adc 100644
--- a/media/cast/BUILD.gn
+++ b/media/cast/BUILD.gn
@@ -2,6 +2,7 @@
 # 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")
 import("//testing/test.gni")
 
 component("cast") {
@@ -397,7 +398,7 @@ executable("udp_proxy") {
   ]
 }
 
-if (is_linux && !is_chromeos) {
+if (is_linux && !use_cros_fe) {
   # TODO(GYP): Figure out which of these work and are needed on other platforms.
   test("cast_benchmarks") {
     sources = [