Introduce a new framework for back-and-forth tracked/protected preferences migration.

chrome/chrome_tests_unit.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.
 {
   'targets': [
     {
       # This target contains mocks and test utilities that don't belong in
       # production libraries but are used by more than one test executable.
       'target_name': 'test_support_common',
       'type': 'static_library',
@@ skipping 1141 matching lines @@
         'browser/prefs/pref_hash_store_impl_unittest.cc',
         'browser/prefs/pref_model_associator_unittest.cc',
         'browser/prefs/profile_pref_store_manager_unittest.cc',
         'browser/prefs/proxy_config_dictionary_unittest.cc',
         'browser/prefs/proxy_policy_unittest.cc',
         'browser/prefs/proxy_prefs_unittest.cc',
         'browser/prefs/session_startup_pref_unittest.cc',
         'browser/prefs/tracked/pref_hash_calculator_helper_win_unittest.cc',
         'browser/prefs/tracked/pref_service_hash_store_contents_unittest.cc',
         'browser/prefs/tracked/segregated_pref_store_unittest.cc',
+        'browser/prefs/tracked/tracked_preferences_migration_unittest.cc',
         'browser/prerender/prerender_history_unittest.cc',
         'browser/prerender/prerender_tracker_unittest.cc',
         'browser/prerender/prerender_unittest.cc',
         'browser/prerender/prerender_util_unittest.cc',
         'browser/printing/cloud_print/cloud_print_proxy_service_unittest.cc',
         'browser/printing/print_dialog_cloud_unittest.cc',
         'browser/printing/print_job_unittest.cc',
         'browser/printing/print_preview_dialog_controller_unittest.cc',
         'browser/printing/print_preview_test.cc',
         'browser/printing/print_preview_test.h',
@@ skipping 1658 matching lines @@
             'browser/ui/app_list/test/fake_profile_store.h',
             'browser/ui/app_list/test/fast_show_pickler_unittest.cc',
             'browser/ui/views/app_list/linux/app_list_linux_unittest.cc',
             'browser/ui/views/app_list/win/app_list_win_unittest.cc',
           ],
         },
       ],
     }],
   ],  # 'conditions'
 }