[SyncFS] Drop test only un-thread-safe getters from SyncEngine (4)

chrome/browser/sync_file_system/drive_backend/sync_worker.h

 // Copyright 2014 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 CHROME_BROWSER_SYNC_FILE_SYSTEM_DRIVE_BACKEND_SYNC_WORKER_H_
 #define CHROME_BROWSER_SYNC_FILE_SYSTEM_DRIVE_BACKEND_SYNC_WORKER_H_
 
 #include <set>
 #include <string>
 
@@ skipping 122 matching lines @@
   drive::DriveServiceInterface* GetDriveService();
   drive::DriveUploaderInterface* GetDriveUploader();
   MetadataDatabase* GetMetadataDatabase();
   SyncTaskManager* GetSyncTaskManager();
 
   void AddObserver(Observer* observer);
 
   void DetachFromSequence();
 
  private:
+  friend class DriveBackendSyncTest;
   friend class SyncEngineTest;
 
   void DoDisableApp(const std::string& app_id,
                     const SyncStatusCallback& callback);
   void DoEnableApp(const std::string& app_id,
                    const SyncStatusCallback& callback);
 
   void PostInitializeTask();
   void DidInitialize(SyncEngineInitializer* initializer,
                      SyncStatusCode status);
@@ skipping 44 matching lines @@
   base::SequenceChecker sequence_checker_;
 
   base::WeakPtrFactory<SyncWorker> weak_ptr_factory_;
   DISALLOW_COPY_AND_ASSIGN(SyncWorker);
 };
 
 }  // namespace drive_backend
 }  // namespace sync_file_system
 
 #endif  // CHROME_BROWSER_SYNC_FILE_SYSTEM_DRIVE_BACKEND_SYNC_WORKER_H_