Rename is_chromeos in chrome/src.

components/session_manager/core/BUILD.gn

Index: components/session_manager/core/BUILD.gn
diff --git a/components/session_manager/core/BUILD.gn b/components/session_manager/core/BUILD.gn
index 9bc5f84c75b86c113814c2459925b283695b71aa..11ad57c8e22f16f40cb71688a0904b675038011c 100644
--- a/components/session_manager/core/BUILD.gn
+++ b/components/session_manager/core/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")
+
 component("core") {
   sources = [
     "../session_manager_export.h",
@@ -11,7 +13,7 @@ component("core") {
   deps = [
     "//base",
   ]
-  if (is_chromeos) {
+  if (use_cros_fe) {
     deps += [ "//chromeos" ]
   }
   defines = [ "SESSION_IMPLEMENTATION" ]