[SyncFS] Remove usage of file task runner under drive_backend/

chrome/browser/sync_file_system/drive_backend/metadata_database.h

 // Copyright 2013 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_METADATA_DATABASE_H_
 #define CHROME_BROWSER_SYNC_FILE_SYSTEM_DRIVE_BACKEND_METADATA_DATABASE_H_
 
 #include <map>
 #include <set>
 #include <string>
@@ skipping 116 matching lines @@
   enum UpdateOption {
     UPDATE_TRACKER_FOR_UNSYNCED_FILE,
     UPDATE_TRACKER_FOR_SYNCED_FILE,
   };
 
   // The entry point of the MetadataDatabase for production code.
   // If |env_override| is non-NULL, internal LevelDB uses |env_override| instead
   // of leveldb::Env::Default().  Use leveldb::MemEnv in test code for faster
   // testing.
   static void Create(base::SequencedTaskRunner* worker_task_runner,
-                     base::SequencedTaskRunner* file_task_runner,
                      const base::FilePath& database_path,
                      leveldb::Env* env_override,
                      const CreateCallback& callback);
   static SyncStatusCode CreateForTesting(
       scoped_ptr<leveldb::DB> db,
       scoped_ptr<MetadataDatabase>* metadata_database_out);
 
   ~MetadataDatabase();
 
   static void ClearDatabase(scoped_ptr<MetadataDatabase> metadata_database);
@@ skipping 195 matching lines @@
   bool GetConflictingTrackers(TrackerIDSet* trackers);
 
   // Sets |app_ids| to a list of all registered app ids.
   void GetRegisteredAppIDs(std::vector<std::string>* app_ids);
 
  private:
   friend class MetadataDatabaseTest;
   struct CreateParam;
 
   MetadataDatabase(base::SequencedTaskRunner* worker_task_runner,
-                   base::SequencedTaskRunner* file_task_runner,
                    const base::FilePath& database_path,
                    leveldb::Env* env_override);
-  static void CreateOnFileTaskRunner(
+  static void CreateOnWorkerTaskRunner(
       scoped_ptr<CreateParam> create_param,
       const CreateCallback& callback);
-  SyncStatusCode InitializeOnFileTaskRunner();
+  SyncStatusCode Initialize();
 
   // Database manipulation methods.
   void RegisterTrackerAsAppRoot(const std::string& app_id,
                                 int64 tracker_id,
                                 leveldb::WriteBatch* batch);
 
   void CreateTrackerForParentAndFileID(const FileTracker& parent_tracker,
                                        const std::string& file_id,
                                        leveldb::WriteBatch* batch);
   void CreateTrackerForParentAndFileMetadata(const FileTracker& parent_tracker,
@@ skipping 41 matching lines @@
                             leveldb::WriteBatch* batch);
 
   void ForceActivateTrackerByPath(int64 parent_tracker_id,
                                   const std::string& title,
                                   const std::string& file_id,
                                   leveldb::WriteBatch* batch);
 
   void DetachFromSequence();
 
   scoped_refptr<base::SequencedTaskRunner> worker_task_runner_;
-  scoped_refptr<base::SequencedTaskRunner> file_task_runner_;
   base::FilePath database_path_;
   leveldb::Env* env_override_;
   scoped_ptr<leveldb::DB> db_;
 
   int64 largest_known_change_id_;
 
   scoped_ptr<MetadataDatabaseIndexInterface> index_;
 
   base::WeakPtrFactory<MetadataDatabase> weak_ptr_factory_;
 
   base::SequenceChecker worker_sequence_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(MetadataDatabase);
 };
 
 }  // namespace drive_backend
 }  // namespace sync_file_system
 
 #endif  // CHROME_BROWSER_SYNC_FILE_SYSTEM_DRIVE_BACKEND_METADATA_DATABASE_H_