Add a windows_xfa_clang trybot and enable clang_use_chrome_plugins

scripts/slave/recipes/pdfium.py

 # 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.
 
 DEPS = [
   'depot_tools/gclient',
   'depot_tools/bot_update',
   'recipe_engine/path',
   'recipe_engine/platform',
   'recipe_engine/properties',
@@ skipping 62 matching lines @@
   checkout = api.path['checkout']
   gn_cmd = api.path['depot_tools'].join('gn.py')
 
   # Prepare the arguments to pass in.
   args = [
       'is_debug=%s' % gn_bool[not rel],
       'pdf_enable_v8=%s' % gn_bool[v8],
       'pdf_enable_xfa=%s' % gn_bool[xfa],
       'pdf_use_skia=%s' % gn_bool[skia],
       'pdf_is_standalone=true',
-      'clang_use_chrome_plugins=false',
   ]
   if target_os:
     args.append('target_os="%s"' % target_os)
 
   api.python('gn gen', gn_cmd,
              ['--root=' + str(checkout), 'gen', '//out/' + out_dir,
               '--args=' + ' '.join(args)],
              cwd=checkout)
 
 def _BuildSteps(api, out_dir):
@@ skipping 389 matching lines @@
   yield (
       api.test('android') +
       api.platform('linux', 64) +
       api.properties(mastername='client.pdfium',
                      buildername='android',
                      slavename='test_slave',
                      target_os='android',
                      gn=True,
                      skip_test=True)
   )