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

chrome/browser/sync_file_system/drive_backend/register_app_task_unittest.cc

 // 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.
 
 #include "chrome/browser/sync_file_system/drive_backend/register_app_task.h"
 
 #include <vector>
 
 #include "base/files/scoped_temp_dir.h"
 #include "base/format_macros.h"
@@ skipping 107 matching lines @@
     PutFileTrackerToDB(sync_root_tracker, db);
     EXPECT_TRUE(db->Commit().ok());
   }
 
   void CreateMetadataDatabase(scoped_ptr<LevelDBWrapper> db) {
     ASSERT_TRUE(db);
     ASSERT_FALSE(context_->GetMetadataDatabase());
     scoped_ptr<MetadataDatabase> metadata_db;
     ASSERT_EQ(SYNC_STATUS_OK,
               MetadataDatabase::CreateForTesting(
-                  db.Pass(), &metadata_db));
+                  db.Pass(), true /* enable_on_disk_index */, &metadata_db));
     context_->SetMetadataDatabase(metadata_db.Pass());
   }
 
   SyncStatusCode RunRegisterAppTask(const std::string& app_id) {
     RegisterAppTask task(context_.get(), app_id);
     SyncStatusCode status = SYNC_STATUS_UNKNOWN;
     task.RunExclusive(CreateResultReceiver(&status));
     base::RunLoop().RunUntilIdle();
     return status;
   }
@@ skipping 167 matching lines @@
 
   CreateMetadataDatabase(db.Pass());
   RunRegisterAppTask(kAppID);
 
   EXPECT_EQ(1u, CountRegisteredAppRoot());
   EXPECT_TRUE(IsAppRegistered(kAppID));
 }
 
 }  // namespace drive_backend
 }  // namespace sync_file_system