Make enable_service_discovery a chrome/ feature.

build/config/features.gni

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # =============================================
 #   PLEASE DO NOT ADD MORE FLAGS TO THIS FILE
 # =============================================
 #
 # These flags are effectively global. Your feature flag should go near the
 # code it controls. Most of these items are here now because they control
@@ skipping 142 matching lines @@
 
 enable_task_manager = !is_ios && !is_android
 
 enable_themes = !is_android && !is_ios
 
 # Whether we are using the rlz library or not.  Platforms like Android send
 # rlz codes for searches but do not use the library.
 enable_rlz_support = is_win || is_mac || is_ios || is_chromeos
 enable_rlz = is_chrome_branded && enable_rlz_support
 
-enable_service_discovery = enable_mdns || is_mac
-
 # Image loader extension is enabled on ChromeOS only.
 enable_image_loader_extension = is_chromeos
 
 # Chrome OS: whether to also build the upcoming version of
 # ChromeVox, which can then be enabled via a command-line switch.
 enable_chromevox_next = false
 
 # Use brlapi from brltty for braille display support.
 use_brlapi = is_chromeos
 
 enable_configuration_policy = !is_ios
 
 enable_mac_keystone = is_mac && is_chrome_branded && is_official_build
 #
 # =============================================
 #   PLEASE DO NOT ADD MORE FLAGS TO THIS FILE
 # =============================================
 #
 # See comment at the top.