[fsp] Improve performance for reading small chunks of data.

chrome/browser/sync_file_system/local/sync_file_system_backend.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/local/sync_file_system_backend.h"
 
+#include <string>
+
 #include "base/logging.h"
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/sync_file_system/local/local_file_change_tracker.h"
 #include "chrome/browser/sync_file_system/local/local_file_sync_context.h"
 #include "chrome/browser/sync_file_system/local/syncable_file_system_operation.h"
 #include "chrome/browser/sync_file_system/sync_file_system_service.h"
 #include "chrome/browser/sync_file_system/sync_file_system_service_factory.h"
 #include "chrome/browser/sync_file_system/syncable_file_system_util.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/notification_service.h"
@@ skipping 159 matching lines @@
 
 bool SyncFileSystemBackend::HasInplaceCopyImplementation(
     storage::FileSystemType type) const {
   return false;
 }
 
 scoped_ptr<storage::FileStreamReader>
 SyncFileSystemBackend::CreateFileStreamReader(
     const storage::FileSystemURL& url,
     int64 offset,
+    int64 length,
     const base::Time& expected_modification_time,
     storage::FileSystemContext* context) const {
   DCHECK(CanHandleType(url.type()));
   return GetDelegate()->CreateFileStreamReader(
       url, offset, expected_modification_time, context);
 }
 
 scoped_ptr<storage::FileStreamWriter>
 SyncFileSystemBackend::CreateFileStreamWriter(
     const storage::FileSystemURL& url,
@@ skipping 95 matching lines @@
                  SyncStatusCodeToFileError(status));
     return;
   }
 
   callback.Run(GetSyncableFileSystemRootURI(origin_url),
                GetFileSystemName(origin_url, type),
                base::File::FILE_OK);
 }
 
 }  // namespace sync_file_system