[SyncFS] Make on-disk version default for metadata database index

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 121 matching lines @@
   // 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(
       const scoped_refptr<base::SequencedTaskRunner>& worker_task_runner,
       const base::FilePath& database_path,
       leveldb::Env* env_override,
       const CreateCallback& callback);
   static SyncStatusCode CreateForTesting(
       scoped_ptr<LevelDBWrapper> db,
+      bool enable_on_disk_index,
       scoped_ptr<MetadataDatabase>* metadata_database_out);
 
   ~MetadataDatabase();
 
   static void ClearDatabase(scoped_ptr<MetadataDatabase> metadata_database);
 
   int64 GetLargestFetchedChangeID() const;
   int64 GetSyncRootTrackerID() const;
   bool HasSyncRoot() const;
 
@@ skipping 199 matching lines @@
   void SweepDirtyTrackers(const std::vector<std::string>& file_ids,
                           const SyncStatusCallback& callback);
 
  private:
   friend class MetadataDatabaseTest;
   struct CreateParam;
 
   MetadataDatabase(
       const scoped_refptr<base::SequencedTaskRunner>& worker_task_runner,
       const base::FilePath& database_path,
+      bool enable_on_disk_index,
       leveldb::Env* env_override);
   static void CreateOnWorkerTaskRunner(
       scoped_ptr<CreateParam> create_param,
       const CreateCallback& callback);
   SyncStatusCode Initialize();
 
   // Database manipulation methods.
   void RegisterTrackerAsAppRoot(const std::string& app_id,
                                 int64 tracker_id);
 
@@ skipping 40 matching lines @@
                                   const std::string& file_id);
 
   void DetachFromSequence();
   bool CanClearDirty(const FileTracker& tracker);
 
   scoped_refptr<base::SequencedTaskRunner> worker_task_runner_;
   base::FilePath database_path_;
   leveldb::Env* env_override_;
   scoped_ptr<LevelDBWrapper> db_;
 
+  bool enable_on_disk_index_;
+
   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_