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

webkit/browser/fileapi/plugin_private_file_system_backend.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 WEBKIT_BROWSER_FILEAPI_PLUGIN_PRIVATE_FILE_SYSTEM_BACKEND_H_
 #define WEBKIT_BROWSER_FILEAPI_PLUGIN_PRIVATE_FILE_SYSTEM_BACKEND_H_
 
 #include <set>
 #include <string>
 
@@ skipping 60 matching lines @@
   virtual FileSystemOperation* CreateFileSystemOperation(
       const FileSystemURL& url,
       FileSystemContext* context,
       base::File::Error* error_code) const OVERRIDE;
   virtual bool SupportsStreaming(const FileSystemURL& url) const OVERRIDE;
   virtual bool HasInplaceCopyImplementation(
       fileapi::FileSystemType type) const OVERRIDE;
   virtual scoped_ptr<webkit_blob::FileStreamReader> CreateFileStreamReader(
       const FileSystemURL& url,
       int64 offset,
+      int64 length,
       const base::Time& expected_modification_time,
       FileSystemContext* context) const OVERRIDE;
   virtual scoped_ptr<FileStreamWriter> CreateFileStreamWriter(
       const FileSystemURL& url,
       int64 offset,
       FileSystemContext* context) const OVERRIDE;
   virtual FileSystemQuotaUtil* GetQuotaUtil() OVERRIDE;
 
   // FileSystemQuotaUtil overrides.
   virtual base::File::Error DeleteOriginDataOnFileTaskRunner(
@@ skipping 47 matching lines @@
   scoped_ptr<AsyncFileUtil> file_util_;
   FileSystemIDToPluginMap* plugin_map_;  // Owned by file_util_.
   base::WeakPtrFactory<PluginPrivateFileSystemBackend> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(PluginPrivateFileSystemBackend);
 };
 
 }  // namespace fileapi
 
 #endif  // WEBKIT_BROWSER_FILEAPI_PLUGIN_PRIVATE_FILE_SYSTEM_BACKEND_H_