Convert ENABLE_WAYLAND_SERVER to a build flag.

chrome/common/features.gni

 # Copyright 2015 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.
 
 import("//build/config/chrome_build.gni")
 import("//build/config/chromecast_build.gni")
 import("//build/config/compiler/compiler.gni")
 import("//build/config/features.gni")
 import("//extensions/features/features.gni")
 import("//media/media_options.gni")
@@ skipping 41 matching lines @@
 
   # Enables use of the session service, which is enabled by default.
   # Android stores them separately on the Java side.
   enable_session_service = !is_android && !is_ios && !is_chromecast
 
   enable_supervised_users = !is_ios && !is_chromecast
 
   # Enables vr shell UI development on local or remote page.
   enable_vr_shell_ui_dev = false
 
+  # Indicates if Wayland display server support is enabled.
+  enable_wayland_server = is_chromeos
+
   # Enable native notifications via XPC services (mac only).
   # TODO(miguelg): remove this.
   enable_xpc_notifications = true
 
   # Indicates if the build is using PGO.
   pgo_build = chrome_pgo_phase > 0
 
   # Optimize parts of Chrome's UI written with web technologies (HTML/CSS/JS)
   # for runtime performance purposes. This does more work at compile time for
   # speed benefits at runtime (so we skip in debug builds). TODO(dbeam): rename
@@ skipping 18 matching lines @@
   "enable_plugins=$enable_plugins",
   "enable_print_preview=$enable_print_preview",
   "enable_printing=$_enable_printing",
   "enable_service_discovery=$enable_service_discovery",
   "enable_webrtc=$enable_webrtc",
   "enable_webvr=$enable_webvr",
   "mac_views_browser=$mac_views_browser",
   "safe_browsing_mode=$safe_browsing_mode",
   "use_vulcanize=$use_vulcanize",
 ]