[Sync] SyncEngine refactor part 2: SyncServiceBase.

components/sync/driver/sync_service_base.h

+// Copyright 2016 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_SYNC_SERVICE_BASE_H_
+#define COMPONENTS_SYNC_DRIVER_SYNC_SERVICE_BASE_H_
+
+#include <memory>
+#include <string>
+
+#include "base/files/file_path.h"
+#include "base/memory/weak_ptr.h"
+#include "base/threading/thread.h"
+#include "components/sync/base/sync_prefs.h"
+#include "components/sync/base/unrecoverable_error_handler.h"
+#include "components/sync/base/weak_handle.h"
+#include "components/sync/driver/signin_manager_wrapper.h"
+#include "components/sync/driver/sync_client.h"
+#include "components/sync/driver/sync_service.h"
+#include "components/sync/engine/sync_engine.h"
+#include "components/sync/engine/sync_engine_host.h"
+#include "components/sync/engine/sync_manager.h"
+#include "components/sync/js/sync_js_controller.h"
+#include "components/version_info/version_info.h"
+
+namespace syncer {
+
+// This is a base class for implementations of SyncService that contains some
+// common functionality and member variables. Anything that can live inside the
+// sync component should eventually live here instead of a concrete
+// implementation. This is set up as a base class so things can be transferred
+// piece by piece as easily as possible.
+class SyncServiceBase : public SyncService, public SyncEngineHost {
+ public:
+  SyncServiceBase(std::unique_ptr<SyncClient> sync_client,
+                  std::unique_ptr<SigninManagerWrapper> signin,
+                  const version_info::Channel& channel,
+                  const base::FilePath& base_directory,
+                  const std::string& debug_identifier);
+  ~SyncServiceBase() override;
+
+ protected:
+  // Kicks off asynchronous initialization of the SyncEngine.
+  void InitializeEngine();
+
+  // Returns SyncCredentials from the OAuth2TokenService.
+  virtual SyncCredentials GetCredentials() = 0;
+
+  // Returns a weak handle to the JsEventHandler.
+  virtual WeakHandle<JsEventHandler> GetJsEventHandler() = 0;
+
+  // Returns a callback that makes an HttpPostProviderFactory.
+  virtual SyncEngine::HttpPostProviderFactoryGetter
+  MakeHttpPostProviderFactoryGetter() = 0;
+
+  // Takes the previously saved nigori state; null if there isn't any.
+  virtual std::unique_ptr<SyncEncryptionHandler::NigoriState>
+  MoveSavedNigoriState() = 0;
+
+  // Returns a weak handle to an UnrecoverableErrorHandler (may be |this|).
+  virtual WeakHandle<UnrecoverableErrorHandler>
+  GetUnrecoverableErrorHandler() = 0;
+
+  // This profile's SyncClient, which abstracts away non-Sync dependencies and
+  // the Sync API component factory.
+  const std::unique_ptr<SyncClient> sync_client_;
+
+  // Encapsulates user signin - used to set/get the user's authenticated
+  // email address.
+  const std::unique_ptr<SigninManagerWrapper> signin_;
+
+  // The product channel of the embedder.
+  const version_info::Channel channel_;
+
+  // The path to the base directory under which sync should store its
+  // information.
+  const base::FilePath base_directory_;
+
+  // The full path to the sync data directory.
+  const base::FilePath directory_path_;
+
+  // An identifier representing this instance for debugging purposes.
+  const std::string debug_identifier_;
+
+  // The class that handles getting, setting, and persisting sync
+  // preferences.
+  SyncPrefs sync_prefs_;
+
+  // The thread where all the sync operations happen. This thread is kept alive
+  // until browser shutdown and reused if sync is turned off and on again. It is
+  // joined during the shutdown process, but there is an abort mechanism in
+  // place to prevent slow HTTP requests from blocking browser shutdown.
+  std::unique_ptr<base::Thread> sync_thread_;
+
+  // Our asynchronous engine to communicate with sync components living on
+  // other threads.
+  std::unique_ptr<SyncEngine> engine_;
+
+ private:
+  bool GetLocalSyncConfig(base::FilePath* local_sync_backend_folder) const;
+
+  DISALLOW_COPY_AND_ASSIGN(SyncServiceBase);
+};
+
+}  // namespace syncer
+
+#endif  // COMPONENTS_SYNC_DRIVER_SYNC_SERVICE_BASE_H_