[Sync] Move sync thread ownership to ProfileSyncService.

components/sync/driver/glue/sync_backend_host.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.
 
 #ifndef COMPONENTS_SYNC_DRIVER_GLUE_SYNC_BACKEND_HOST_H_
 #define COMPONENTS_SYNC_DRIVER_GLUE_SYNC_BACKEND_HOST_H_
 
 #include <memory>
 #include <string>
 
@@ skipping 41 matching lines @@
   ~SyncBackendHost() override;
 
   // Called on the frontend's thread to kick off asynchronous initialization.
   // Optionally deletes the "Sync Data" folder during init in order to make
   // sure we're starting fresh.
   //
   // |saved_nigori_state| is optional nigori state to restore from a previous
   // backend instance. May be null.
   virtual void Initialize(
       SyncFrontend* frontend,
-      std::unique_ptr<base::Thread> sync_thread,
+      base::Thread* sync_thread,
       const scoped_refptr<base::SingleThreadTaskRunner>& db_thread,
       const scoped_refptr<base::SingleThreadTaskRunner>& file_thread,
       const WeakHandle<JsEventHandler>& event_handler,
       const GURL& service_url,
       const std::string& sync_user_agent,
       const SyncCredentials& credentials,
       bool delete_sync_data_folder,
       bool enable_local_sync_backend,
       const base::FilePath& local_sync_backend_folder,
       std::unique_ptr<SyncManagerFactory> sync_manager_factory,
@@ skipping 39 matching lines @@
       WARN_UNUSED_RESULT = 0;
 
   // Called on |frontend_loop_| to kick off shutdown procedure.  Attempts to cut
   // short any long-lived or blocking sync thread tasks so that the shutdown on
   // sync thread task that we're about to post won't have to wait very long.
   virtual void StopSyncingForShutdown() = 0;
 
   // Called on |frontend_loop_| to kick off shutdown.
   // See the implementation and Core::DoShutdown for details.
   // Must be called *after* StopSyncingForShutdown.
-  // Transfers ownership of the sync thread to the caller which may reuse it
-  // with a different SyncBackendHost or join it immediately.
-  virtual std::unique_ptr<base::Thread> Shutdown(ShutdownReason reason) = 0;
+  virtual void Shutdown(ShutdownReason reason) = 0;
 
   // Removes all current registrations from the backend on the
   // InvalidationService.
   virtual void UnregisterInvalidationIds() = 0;
 
   // Changes the set of data types that are currently being synced.
   // The ready_task will be run when configuration is done with the
   // set of all types that failed configuration (i.e., if its argument
   // is non-empty, then an error was encountered).
   // Returns the set of types that are ready to start without needing any
@@ skipping 54 matching lines @@
   virtual void DisableProtocolEventForwarding() = 0;
 
   // Enables the sending of directory type debug counters.  Also, for every
   // time it is called, it makes an explicit request that updates to an update
   // for all counters be emitted.
   virtual void EnableDirectoryTypeDebugInfoForwarding() = 0;
 
   // Disables the sending of directory type debug counters.
   virtual void DisableDirectoryTypeDebugInfoForwarding() = 0;
 
-  virtual base::MessageLoop* GetSyncLoopForTesting() = 0;
-
   // Triggers sync cycle to update |types|.
   virtual void RefreshTypesForTest(ModelTypeSet types) = 0;
 
   // See SyncManager::ClearServerData.
   virtual void ClearServerData(
       const SyncManager::ClearServerDataCallback& callback) = 0;
 
   // Notify the syncer that the cookie jar has changed.
   // See SyncManager::OnCookieJarChanged.
   virtual void OnCookieJarChanged(bool account_mismatch, bool empty_jar) = 0;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(SyncBackendHost);
 };
 
 }  // namespace syncer
 
 #endif  // COMPONENTS_SYNC_DRIVER_GLUE_SYNC_BACKEND_HOST_H_