sync: Gracefully handle very early shutdown

sync/internal_api/public/internal_components_factory.h

 // 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.
 //
 // InternalComponentsFactory exists so that tests can override creation of
 // components used by the SyncManager that are not exposed across the sync
 // API boundary.
 
 #ifndef SYNC_INTERNAL_API_PUBLIC_INTERNAL_COMPONENTS_FACTORY_H_
 #define SYNC_INTERNAL_API_PUBLIC_INTERNAL_COMPONENTS_FACTORY_H_
 
 #include <string>
 #include <vector>
 
 #include "base/files/file_path.h"
 #include "sync/base/sync_export.h"
 #include "sync/internal_api/public/engine/model_safe_worker.h"
 
 namespace syncer {
 
 class ExtensionsActivity;
 class ServerConnectionManager;
 class SyncEngineEventListener;
+class CancelationSignal;
 class SyncScheduler;
 class TrafficRecorder;
 
 namespace sessions {
 class DebugInfoGetter;
 class SyncSessionContext;
 }
 
 namespace syncable {
 class Directory;
@@ skipping 34 matching lines @@
   struct Switches {
     EncryptionMethod encryption_method;
     BackoffOverride backoff_override;
     PreCommitUpdatesPolicy pre_commit_updates_policy;
   };
 
   virtual ~InternalComponentsFactory() {}
 
   virtual scoped_ptr<SyncScheduler> BuildScheduler(
       const std::string& name,
-      sessions::SyncSessionContext* context) = 0;
+      sessions::SyncSessionContext* context,
+      CancelationSignal* cancelation_signal) = 0;
 
   virtual scoped_ptr<sessions::SyncSessionContext> BuildContext(
       ServerConnectionManager* connection_manager,
       syncable::Directory* directory,
       const std::vector<ModelSafeWorker*>& workers,
       ExtensionsActivity* extensions_activity,
       const std::vector<SyncEngineEventListener*>& listeners,
       sessions::DebugInfoGetter* debug_info_getter,
       TrafficRecorder* traffic_recorder,
       const std::string& invalidator_client_id) = 0;
 
   virtual scoped_ptr<syncable::DirectoryBackingStore>
   BuildDirectoryBackingStore(
       const std::string& dir_name,
       const base::FilePath& backing_filepath) = 0;
 
   // Returns the Switches struct that this object is using as configuration, if
   // the implementation is making use of one.
   virtual Switches GetSwitches() const = 0;
 };
 
 }  // namespace syncer
 
 #endif  // SYNC_INTERNAL_API_PUBLIC_INTERNAL_COMPONENTS_FACTORY_H_