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

chrome/browser/chromeos/fileapi/mtp_file_system_backend_delegate.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_CHROMEOS_FILEAPI_MTP_FILE_SYSTEM_BACKEND_DELEGATE_H_
 #define CHROME_BROWSER_CHROMEOS_FILEAPI_MTP_FILE_SYSTEM_BACKEND_DELEGATE_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "chrome/browser/chromeos/fileapi/file_system_backend_delegate.h"
 
@@ skipping 21 matching lines @@
   explicit MTPFileSystemBackendDelegate(
       const base::FilePath& storage_partition_path);
   virtual ~MTPFileSystemBackendDelegate();
 
   // FileSystemBackendDelegate overrides.
   virtual storage::AsyncFileUtil* GetAsyncFileUtil(
       storage::FileSystemType type) OVERRIDE;
   virtual scoped_ptr<storage::FileStreamReader> CreateFileStreamReader(
       const storage::FileSystemURL& url,
       int64 offset,
+      int64 max_bytes_to_read,
       const base::Time& expected_modification_time,
       storage::FileSystemContext* context) OVERRIDE;
   virtual scoped_ptr<storage::FileStreamWriter> CreateFileStreamWriter(
       const storage::FileSystemURL& url,
       int64 offset,
       storage::FileSystemContext* context) OVERRIDE;
   virtual storage::WatcherManager* GetWatcherManager(
       const storage::FileSystemURL& url) OVERRIDE;
   virtual void GetRedirectURLForContents(
       const storage::FileSystemURL& url,
       const storage::URLCallback& callback) OVERRIDE;
 
  private:
   scoped_ptr<DeviceMediaAsyncFileUtil> device_media_async_file_util_;
 
   DISALLOW_COPY_AND_ASSIGN(MTPFileSystemBackendDelegate);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_FILEAPI_MTP_FILE_SYSTEM_BACKEND_DELEGATE_H_