Move enable_pdf to a buildflag header.

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.")
-}