Introduce GN to desktop_linux arg and grit_defines list.

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() {
+  desktop_linux = is_linux && !is_chromeos

[brettw, 2014/05/27 23:54:23]

Since it seems like we're stuck with this, can you put this in
build/common/BUILDCONFIG.gn where the other is_linux, etc are defined, and call
it is_desktop_linux?

[tfarina, 2014/05/30 03:02:07]

Done.

+
   # 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_chromeos
 
   # Indicates if Ozone is enabled. Ozone is a low-level library layer for Linux
   # that does not require X11.
   use_ozone = false
 
   # Indicates if Aura is enabled. Aura is a low-level windowing library, sort
   # of a replacement for GDI or GTK.
@@ skipping 24 matching lines @@
 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 = is_linux && !use_ozone
 
 use_glib = is_linux
 
 use_clipboard_aurax11 = is_linux && use_aura && use_x11
+
+grit_defines = []

[tfarina, 2014/05/23 19:38:37]

in GYP this is declared in build/common.gypi.

Where in GN would be a better place for this?

[brettw, 2014/05/27 23:51:03]

I think you can just put this in the grit_rule.gni file itself, unless it needs
to be used outside of that file.

[tfarina, 2014/05/30 03:02:07]

Done.

+if (is_chromeos) {
+  grit_defines += [ "-D", "chromeos", "-D", "scale_factors=2x"]
+}
+
+if (desktop_linux) {
+  grit_defines += [ "-D", "desktop_linux" ]
+}