Add a Restore() method to ValueStore and make StorageAPI use it

chrome/chrome_browser_extensions.gypi

 # Copyright (c) 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': [
     {
       'target_name': 'browser_extensions',
       'type': 'static_library',
       'variables': { 'enable_wexit_time_destructors': 1, },
@@ skipping 490 matching lines @@
         'browser/extensions/api/sockets_tcp_server/sockets_tcp_server_api.cc',
         'browser/extensions/api/sockets_tcp_server/sockets_tcp_server_api.h',
         'browser/extensions/api/sockets_udp/udp_socket_event_dispatcher.h',
         'browser/extensions/api/sockets_udp/udp_socket_event_dispatcher.cc',
         'browser/extensions/api/sockets_udp/sockets_udp_api.cc',
         'browser/extensions/api/sockets_udp/sockets_udp_api.h',
         'browser/extensions/api/spellcheck/spellcheck_api.cc',
         'browser/extensions/api/spellcheck/spellcheck_api.h',
         'browser/extensions/api/storage/leveldb_settings_storage_factory.cc',
         'browser/extensions/api/storage/leveldb_settings_storage_factory.h',
+        'browser/extensions/api/storage/local_storage_backend.cc',
+        'browser/extensions/api/storage/local_storage_backend.h',
         'browser/extensions/api/storage/managed_value_store_cache.cc',
         'browser/extensions/api/storage/managed_value_store_cache.h',
         'browser/extensions/api/storage/policy_value_store.cc',
         'browser/extensions/api/storage/policy_value_store.h',
         'browser/extensions/api/storage/setting_sync_data.cc',
         'browser/extensions/api/storage/setting_sync_data.h',
         'browser/extensions/api/storage/settings_backend.cc',
         'browser/extensions/api/storage/settings_backend.h',
         'browser/extensions/api/storage/settings_frontend.cc',
         'browser/extensions/api/storage/settings_frontend.h',
         'browser/extensions/api/storage/settings_namespace.cc',
         'browser/extensions/api/storage/settings_namespace.h',
         'browser/extensions/api/storage/settings_observer.h',
         'browser/extensions/api/storage/settings_storage_factory.h',
         'browser/extensions/api/storage/settings_storage_quota_enforcer.cc',
         'browser/extensions/api/storage/settings_storage_quota_enforcer.h',
         'browser/extensions/api/storage/settings_sync_processor.cc',
         'browser/extensions/api/storage/settings_sync_processor.h',
         'browser/extensions/api/storage/settings_sync_util.cc',
         'browser/extensions/api/storage/settings_sync_util.h',
         'browser/extensions/api/storage/storage_api.cc',
         'browser/extensions/api/storage/storage_api.h',
         'browser/extensions/api/storage/sync_or_local_value_store_cache.cc',
         'browser/extensions/api/storage/sync_or_local_value_store_cache.h',
+        'browser/extensions/api/storage/sync_storage_backend.cc',
+        'browser/extensions/api/storage/sync_storage_backend.h',
         'browser/extensions/api/storage/syncable_settings_storage.cc',
         'browser/extensions/api/storage/syncable_settings_storage.h',
         'browser/extensions/api/storage/value_store_cache.cc',
         'browser/extensions/api/storage/value_store_cache.h',
         'browser/extensions/api/storage/weak_unlimited_settings_storage.cc',
         'browser/extensions/api/storage/weak_unlimited_settings_storage.h',
         'browser/extensions/api/streams_private/streams_private_api.cc',
         'browser/extensions/api/streams_private/streams_private_api.h',
         'browser/extensions/api/sync_file_system/extension_sync_event_observer_factory.cc',
         'browser/extensions/api/sync_file_system/extension_sync_event_observer_factory.h',
@@ skipping 697 matching lines @@
           'variables': {
             'proto_in_dir': 'browser/chromeos/contacts',
             'proto_out_dir': 'chrome/browser/chromeos/contacts',
           },
           'includes': [ '../build/protoc.gypi' ]
         },
       ],
     },],  # 'chromeos=1'
   ],  # 'conditions'
 }