Use FileTypePolicies for download danger classifications.

chrome/chrome_browser.gypi

 # Copyright 2012 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.
 
 {
   'variables': {
     # All .cc, .h, .m, and .mm files under browser except for:
     # * tests and mocks.
     # * code below browser/chromeos
     # * code below browser/extensions
@@ skipping 184 matching lines @@
       'browser/dom_distiller/profile_utils.h',
       'browser/dom_distiller/tab_utils.cc',
       'browser/dom_distiller/tab_utils.h',
       'browser/domain_reliability/service_factory.cc',
       'browser/domain_reliability/service_factory.h',
       'browser/download/all_download_item_notifier.cc',
       'browser/download/all_download_item_notifier.h',
       'browser/download/chrome_download_manager_delegate.cc',
       'browser/download/chrome_download_manager_delegate.h',
       'browser/download/download_crx_util_android.cc',
-      'browser/download/download_extensions.cc',
-      'browser/download/download_extensions.h',
       'browser/download/download_file_picker.cc',
       'browser/download/download_file_picker.h',
       'browser/download/download_history.cc',
       'browser/download/download_history.h',
       'browser/download/download_item_model.cc',
       'browser/download/download_item_model.h',
       'browser/download/download_path_reservation_tracker.cc',
       'browser/download/download_path_reservation_tracker.h',
       'browser/download/download_prefs.cc',
       'browser/download/download_prefs.h',
@@ skipping 4040 matching lines @@
             '../components/components.gyp:rlz',
             '../components/components.gyp:search_engines',
             '../rlz/rlz.gyp:rlz_lib',
             'common',
           ],
         },
       ],
     }],
   ],
 }