headless: Add gn settings for embedded build and headless mode

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 Chrome-feature-related build flags (see ui.gni for
 # UI-related ones). These should theoretically be moved to the build files of
 # the features themselves.
 #
 # However, today we have many "bad" dependencies on some of these flags from,
 # e.g. base, so they need to be global to match the GYP configuration. Also,
 # anything that needs a grit define must be in either this file or ui.gni.
 #
 # PLEASE TRY TO AVOID ADDING FLAGS TO THIS FILE in cases where grit isn't
 # required. See the declare_args block of BUILDCONFIG.gn for advice on how
 # to set up feature flags.
 
 import("//build/config/chrome_build.gni")
 import("//build/config/chromecast_build.gni")
+import("//build/config/headless_build.gni")
 if (is_android) {
   import("//build/config/android/config.gni")
 }
 
 declare_args() {
   # Multicast DNS.
   enable_mdns = is_win || is_linux
 
   enable_plugins = (!is_android && !is_ios) || is_chromecast
   enable_pdf = !is_android && !is_ios && !is_chromecast
@@ skipping 50 matching lines @@
   enable_app_list = !is_ios && !is_android
 
   enable_supervised_users = !is_ios
 
   enable_autofill_dialog = !is_ios
 
   enable_google_now = !is_ios && !is_android
 
   enable_one_click_signin = is_win || is_mac || (is_linux && !is_chromeos)
 
-  enable_remoting = !is_ios && !is_android && !is_chromecast
+  enable_remoting = !is_ios && !is_android && !is_chromecast && !is_headless
 
   # Enable hole punching for the protected video.
   enable_video_hole = is_android
 
   # Enables browser side Content Decryption Modules. Required for embedders
   # (e.g. Android and ChromeCast) that use a browser side CDM.
   enable_browser_cdms = is_android || is_chromecast
 
   # Hangout services is an extension that adds extra features to Hangouts.
   # For official GYP builds, this flag is set.
@@ skipping 18 matching lines @@
 }
 
 # Additional dependent variables -----------------------------------------------
 
 # Set the version of CLD.
 #   1: (DEPRECATED! See http://crbug.com/528305 for info) Use only CLD1.
 #   2: Use only CLD2.
 cld_version = 2
 
 # libudev usage. This currently only affects the content layer.
-use_udev = is_linux && !is_chromecast
+use_udev = is_linux && !is_chromecast && !is_headless
 
 # Enable the spell checker.
 enable_spellcheck = !is_ios
 
 # Use the operating system's spellchecker rather than hunspell.
 use_browser_spellchecker = is_android || is_mac
 
 # Enable basic printing support and UI.
-enable_basic_printing = !is_chromeos && !is_chromecast && !is_ios
+enable_basic_printing =
+    !is_chromeos && !is_chromecast && !is_ios && !is_headless
 
 # Enable printing with print preview. It does not imply
 # enable_basic_printing. It's possible to build Chrome with preview only.
-enable_print_preview = !is_android && !is_chromecast && !is_ios
+enable_print_preview = !is_android && !is_chromecast && !is_ios && !is_headless
 
 # Enables the use of CDMs in pepper plugins.
 enable_pepper_cdms =
     enable_plugins && (is_linux || is_mac || is_win) && !is_chromecast
 
 # The seccomp-bpf sandbox is only supported on three architectures
 # currently.
 # Do not disable seccomp_bpf anywhere without talking to
 # security@chromium.org!
 use_seccomp_bpf = (is_linux || is_android) &&
                   (current_cpu == "x86" || current_cpu == "x64" ||
                    current_cpu == "arm" || current_cpu == "mipsel")
 
 # Enable notifications everywhere except iOS.
 enable_notifications = !is_ios
 
 enable_web_speech = !is_android && !is_ios
 
-use_dbus = is_linux && !is_chromecast
+use_dbus = is_linux && !is_chromecast && !is_headless
 
 enable_extensions = !is_android && !is_ios
 
 enable_task_manager = !is_ios && !is_android
 
-use_cups = (is_desktop_linux || is_mac) && !is_chromecast
+use_cups = (is_desktop_linux || is_mac) && !is_chromecast && !is_headless
 
 enable_themes = !is_android && !is_ios
 
 # TODO(scottmg) remove this when we've fixed printing.
 win_pdf_metafile_for_printing = true
 
 # 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_settings_app = enable_app_list && !is_chromeos
 
 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
 
 # Option controlling the use of GConf (the classic GNOME configuration
 # system).
-use_gconf = is_linux && !is_chromeos && !is_chromecast
+use_gconf = is_linux && !is_chromeos && !is_chromecast && !is_headless
 
 # Whether to back up data before sync.
 enable_pre_sync_backup = is_win || is_mac || (is_linux && !is_chromeos)
 
 # Enable WebVR support by default on Android
 # Still requires command line flag to access API
 enable_webvr = is_android
+
+use_gio = is_desktop_linux && !is_headless