Reset user data directory and disk cache directory after downgrade.

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 1461 matching lines @@
       'browser/google/did_run_updater_win.cc',
       'browser/google/did_run_updater_win.h',
       'browser/hang_monitor/hang_crash_dump_win.cc',
       'browser/hang_monitor/hang_crash_dump_win.h',
       'browser/metrics/antivirus_metrics_provider_win.cc',
       'browser/metrics/antivirus_metrics_provider_win.h',
       'browser/password_manager/password_manager_util_win.cc',
       'browser/password_manager/password_manager_util_win.h',
       'browser/themes/theme_service_win.cc',
       'browser/themes/theme_service_win.h',
+      'browser/downgrade/user_data_downgrade.cc',
+      'browser/downgrade/user_data_downgrade.h',
     ],
     'chrome_browser_non_win_sources': [
       'browser/profile_resetter/triggered_profile_resetter_stub.cc',
       'browser/profiles/profile_shortcut_manager_stub.cc',
     ],
     # Sources (generally "desktop OS importers") used only on Mac & Windows.
     'chrome_browser_win_mac_sources': [
       'browser/crash_upload_list_crashpad.cc',
       'browser/crash_upload_list_crashpad.h',
       'browser/media_galleries/fileapi/file_path_watcher_util.cc',
@@ skipping 2786 matching lines @@
             '../components/components.gyp:rlz',
             '../components/components.gyp:search_engines',
             '../rlz/rlz.gyp:rlz_lib',
             'common',
           ],
         },
       ],
     }],
   ],
 }