Add ENABLE_MEDIA_ROUTER define

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.
 
 # This file contains UI-related build flags. It should theoretically be in the
 # src/ui directory and only things that depend on the ui module should get the
 # definitions.
 #
 # However, today we have many "bad" dependencies on some of these flags from,
 # e.g. base, so they need to be global.
@@ skipping 29 matching lines @@
   # If debug_devtools is set to true, JavaScript files for DevTools are stored
   # as is and loaded from disk. Otherwise, a concatenated file is stored in
   # resources.pak. It is still possible to load JS files from disk by passing
   # --debug-devtools cmdline switch.
   debug_devtools = false
 
   # Enables WebRTC.
   # TODO(GYP) make mac and android work.
   enable_webrtc = !is_ios && !is_mac && !is_android
 
+  # Enables the Media Router.
+  enable_media_router = !is_ios && !is_android
+
   # Enables proprietary codecs and demuxers; e.g. H264, MOV, AAC, and MP3.
   proprietary_codecs = false
 
   enable_configuration_policy = true
 
   # Enables support for background apps.
   enable_background = !is_ios && !is_android
 
   enable_captive_portal_detection = !is_android && !is_ios
 
@@ skipping 117 matching lines @@
 # TODO(GYP) also require !embedded to enable.
 use_gconf = is_linux && !is_chromeos
 
 # Hangout services is an extension that adds extra features to Hangouts.
 # For official GYP builds, this flag is set, it will likely need to be
 # parameterized in the future for a similar use.
 enable_hangout_services_extension = false
 
 # Whether to back up data before sync.
 enable_pre_sync_backup = is_win || is_mac || (is_linux && !is_chromeos)