Let SyncBackupManager keep backup data in memory until shutdown. Only persist

sync/sync_tests.gypi

 # Copyright 2013 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': [
     # Test support files for the 'sync_core' target.
     # GN version: //sync:test_support_sync_core
     {
       'target_name': 'test_support_sync_core',
@@ skipping 299 matching lines @@
         'internal_api/sync_rollback_manager_base_unittest.cc',
         'internal_api/sync_rollback_manager_unittest.cc',
         'internal_api/syncapi_server_connection_manager_unittest.cc',
         'js/js_event_details_unittest.cc',
         'js/sync_js_controller_unittest.cc',
         'protocol/proto_enum_conversions_unittest.cc',
         'protocol/proto_value_conversions_unittest.cc',
         'sessions/model_type_registry_unittest.cc',
         'sessions/nudge_tracker_unittest.cc',
         'sessions/status_controller_unittest.cc',
+        'syncable/deferred_on_disk_directory_backing_store_unittest.cc',
         'syncable/directory_backing_store_unittest.cc',
         'syncable/directory_unittest.cc',
         'syncable/directory_unittest.h',
         'syncable/entry_kernel_unittest.cc',
         'syncable/model_type_unittest.cc',
         'syncable/nigori_util_unittest.cc',
         'syncable/parent_child_index_unittest.cc',
         'syncable/syncable_enum_conversions_unittest.cc',
         'syncable/syncable_id_unittest.cc',
         'syncable/syncable_unittest.cc',
@@ skipping 131 matching lines @@
           ],
           'variables': {
             'test_suite_name': 'sync_unit_tests',
           },
           'includes': [ '../build/apk_test.gypi' ],
         },
       ],
     }],
   ],
 }