Ozone X11 platform

build/config/ui.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.
 #
 # See also build/config/features.gni
 
 declare_args() {
   # Indicates if Ash is enabled. Ash is the Aura Shell which provides a
   # desktop-like environment for Aura. Requires use_aura = true
   use_ash = is_win || is_linux
 
   # Indicates if Ozone is enabled. Ozone is a low-level library layer for Linux
   # that does not require X11.
   use_ozone = false
 
+  # Indicates if Ozone should use X11.
+  use_ozone_x11 = false
+
   # Support ChromeOS touchpad gestures with ozone.
   use_evdev_gestures = false
 
   # Indicates if Aura is enabled. Aura is a low-level windowing library, sort
   # of a replacement for GDI or GTK.
   use_aura = is_win || is_linux
 
   # True means the UI is built using the "views" framework.
   toolkit_views = is_win || is_chromeos || use_aura
 }
 
 # Additional dependent variables -----------------------------------------------
 #
 # These variables depend on other variables and can't be set externally.
 
 if (is_linux) {
   use_cairo = true
   use_pango = true
 } else {
   use_cairo = false
   use_pango = false
 }
 
+if (use_ozone_x11) {
+  use_ozone = true
+}
+
 # Use GPU accelerated cross process image transport by default on linux builds
 # with the Aura window manager.
 ui_compositor_image_transport = use_aura && is_linux
 
 use_default_render_theme = use_aura || is_linux
 
 # Indicates if the UI toolkit depends on X11.
+# use_x11 specifies if the entire system uses X11-specific code, use_x11_backend
+# specifies if X11 is used as a backend even if use_x11 is off.
 use_x11 = is_linux && !use_ozone
+use_x11_backend = use_x11 || (is_linux && use_ozone && use_ozone_x11)
 
 use_ozone_evdev = use_ozone
 
 use_glib = is_linux && !use_ozone
 
 use_clipboard_aurax11 = is_linux && use_aura && use_x11
 
 use_athena = false
 
 enable_hidpi = is_mac || is_chromeos || is_win