chrome: Cleanup class/struct forward declarations

chrome/browser/sync_file_system/drive_backend/fake_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_FAKE_SYNC_WORKER_H_
 #define CHROME_BROWSER_SYNC_FILE_SYSTEM_DRIVE_BACKEND_FAKE_SYNC_WORKER_H_
 
 #include <map>
 #include <memory>
 #include <string>
 
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/observer_list.h"
 #include "base/sequence_checker.h"
 #include "chrome/browser/sync_file_system/drive_backend/sync_worker_interface.h"
 #include "chrome/browser/sync_file_system/remote_file_sync_service.h"
 #include "chrome/browser/sync_file_system/sync_callbacks.h"
 #include "net/base/network_change_notifier.h"
 
 class GURL;
 
 namespace base {
 class FilePath;
 class ListValue;
 }
 
-namespace drive {
-class DriveServiceInterface;
-class DriveUploaderInterface;
-}
-
 namespace storage {
 class FileSystemURL;
 }
 
 namespace sync_file_system {
 
 class FileChange;
 class SyncFileMetadata;
 
 namespace drive_backend {
 
-class MetadataDatabase;
 class RemoteChangeProcessorOnWorker;
 class SyncEngineContext;
-class SyncTaskManager;
 
 class FakeSyncWorker : public SyncWorkerInterface {
  public:
   FakeSyncWorker();
   ~FakeSyncWorker() override;
 
   // SyncWorkerInterface overrides.
   void Initialize(
       std::unique_ptr<SyncEngineContext> sync_engine_context) override;
   void RegisterOrigin(const GURL& origin,
@@ skipping 48 matching lines @@
   base::ObserverList<Observer> observers_;
   base::SequenceChecker sequence_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(FakeSyncWorker);
 };
 
 }  // namespace drive_backend
 }  // namespace sync_file_system
 
 #endif  // CHROME_BROWSER_SYNC_FILE_SYSTEM_DRIVE_BACKEND_FAKE_SYNC_WORKER_H_