Move printing defines to buildflag system.

chrome/browser/ui/libgtkui/BUILD.gn

 # 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.
 
 assert(is_linux, "This file should only be referenced on Linux")
 
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
+import("//printing/features/features.gni")
 
 # gn orders flags on a target before flags from configs. The default config
 # adds -Wall, and these flags have to be after -Wall -- so they need to come
 # from a config and can't be on the target directly.
 config("libgtkui_warnings") {
   if (is_clang) {
     cflags = [
       # G_DEFINE_TYPE automatically generates a *get_instance_private inline
       # function after glib 2.37. That's unused. Prevent to complain about it.
       "-Wno-unused-function",
@@ skipping 121 matching lines @@
   defines = [ "LIBGTKUI_IMPLEMENTATION" ]
 
   deps = common_deps + [
            "//build/config/linux/gtk3",
            "//build/config/linux/gtk3:gtkprint3",
          ]
   public_deps = [
     "//chrome/browser:theme_properties",
   ]
 }