Move printing defines to buildflag system.

printing/features/features.gni

+# Copyright 2016 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.
+
+import("//build/config/chromecast_build.gni")
+import("//build/config/features.gni")
+
+declare_args() {
+  # Enable basic printing support and UI.
+  enable_basic_printing = !is_chromecast && !is_ios
+
+  # 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
+
+  use_cups = (is_desktop_linux || is_mac) && !is_chromecast
+}
+
+if ((enable_basic_printing && is_win) || enable_print_preview) {
+  # Windows basic printing or print preview requires pdf enabled.
+  assert(enable_pdf,
+         "Windows basic printing or print preview needs pdf: " +
+             "set enable_pdf=true.")
+}