Rename is_chromeos in chrome/src.

device/media_transfer_protocol/BUILD.gn

Index: device/media_transfer_protocol/BUILD.gn
diff --git a/device/media_transfer_protocol/BUILD.gn b/device/media_transfer_protocol/BUILD.gn
index a36c606e93bb675e245b24bb993685e8eaa10d4e..43a87564b2908d8cdc78abca0c6231d4da02f957 100644
--- a/device/media_transfer_protocol/BUILD.gn
+++ b/device/media_transfer_protocol/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("//third_party/protobuf/proto_library.gni")
 
 # GYP version: device/media_transfer_protocol/media_transfer_protocol.gyp:mtp_file_entry_proto
@@ -38,7 +39,7 @@ static_library("media_transfer_protocol") {
     "//dbus",
   ]
 
-  if (is_chromeos) {
+  if (use_cros_fe) {
     deps += [ "//chromeos" ]
   }
 }