sync: Gracefully handle very early shutdown

sync/sync_internal_api.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.
 
 {
   'include_dirs': [
     '..',
   ],
   'defines': [
     'SYNC_IMPLEMENTATION',
@@ skipping 14 matching lines @@
     'internal_api/debug_info_event_listener.cc',
     'internal_api/debug_info_event_listener.h',
     'internal_api/http_bridge.cc',
     'internal_api/internal_components_factory_impl.cc',
     'internal_api/js_mutation_event_observer.cc',
     'internal_api/js_mutation_event_observer.h',
     'internal_api/js_sync_encryption_handler_observer.cc',
     'internal_api/js_sync_encryption_handler_observer.h',
     'internal_api/js_sync_manager_observer.cc',
     'internal_api/js_sync_manager_observer.h',
+    'internal_api/public/base/cancelation_observer.cc',
+    'internal_api/public/base/cancelation_observer.h',
+    'internal_api/public/base/cancelation_signal.cc',
+    'internal_api/public/base/cancelation_signal.h',
     'internal_api/public/base/enum_set.h',
     'internal_api/public/base/invalidation.cc',
     'internal_api/public/base/invalidation.h',
     'internal_api/public/base/model_type.h',
     'internal_api/public/base/node_ordinal.cc',
     'internal_api/public/base/node_ordinal.h',
     'internal_api/public/base/ordinal.h',
     'internal_api/public/base/progress_marker_map.cc',
     'internal_api/public/base/progress_marker_map.h',
     'internal_api/public/base/unique_position.cc',
@@ skipping 21 matching lines @@
     'internal_api/public/internal_components_factory_impl.h',
     'internal_api/public/internal_components_factory.h',
     'internal_api/public/read_node.h',
     'internal_api/public/read_transaction.h',
     'internal_api/public/sessions/model_neutral_state.cc',
     'internal_api/public/sessions/model_neutral_state.h',
     'internal_api/public/sessions/sync_session_snapshot.cc',
     'internal_api/public/sessions/sync_session_snapshot.h',
     'internal_api/public/sync_encryption_handler.cc',
     'internal_api/public/sync_encryption_handler.h',
-    'internal_api/public/sync_manager_factory.h',
     'internal_api/public/sync_manager.cc',
     'internal_api/public/sync_manager.h',
+    'internal_api/public/sync_manager_factory.h',
     'internal_api/public/user_share.h',
     'internal_api/public/util/experiments.h',
     'internal_api/public/util/immutable.h',
     'internal_api/public/util/report_unrecoverable_error_function.h',
     'internal_api/public/util/sync_string_conversions.cc',
     'internal_api/public/util/sync_string_conversions.h',
     'internal_api/public/util/syncer_error.cc',
     'internal_api/public/util/syncer_error.h',
     'internal_api/public/util/unrecoverable_error_handler.h',
     'internal_api/public/util/unrecoverable_error_info.cc',
@@ skipping 11 matching lines @@
     'internal_api/sync_manager_impl.h',
     'internal_api/syncapi_internal.cc',
     'internal_api/syncapi_internal.h',
     'internal_api/syncapi_server_connection_manager.cc',
     'internal_api/syncapi_server_connection_manager.h',
     'internal_api/user_share.cc',
     'internal_api/write_node.cc',
     'internal_api/write_transaction.cc',
   ],
 }