GN: Work on Linux build defines

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.
+#
+# See also build/config/ui.gni
+
+declare_args() {
+  # Multicast DNS.
+  enable_mdns = is_win || is_linux
+
+  enable_plugins = !is_android || !is_ios
+}
+
+# Additional dependent variables -----------------------------------------------
+
+# Set the version of CLD.
+#   0: Don't specify the version. This option is for the Finch testing.
+#   1: Use only CLD1.
+#   2: Use only CLD2.
+if (is_android || is_ios) {
+  cld_version = 1
+} else {
+  cld_version = 2
+}
+
+# libudev usage. This currently only affects the content layer.
+use_udev = is_linux
+
+# Enable the spell checker.
+enable_spellcheck = !is_android
+
+enable_pepper_cdms = enable_plugins && (is_linux || is_mac || is_win)
+
+# Enable printing support and UI. This variable is used to configure which
+# parts of printing will be built. 0 disables printing completely, 1 enables it
+# fully, and 2 enables only the codepath to generate a Metafile (e.g.  usually
+# a PDF or EMF) and disables print preview, cloud print, UI, etc.
+if (is_android) {
+  enable_printing = 2
+} else {
+  enable_printing = 1
+}