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

chrome/browser/local_discovery/storage/privet_filesystem_backend.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_LOCAL_DISCOVERY_STORAGE_PRIVET_FILESYSTEM_BACKEND_H_
 #define CHROME_BROWSER_LOCAL_DISCOVERY_STORAGE_PRIVET_FILESYSTEM_BACKEND_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 36 matching lines @@
 
   virtual bool SupportsStreaming(
       const fileapi::FileSystemURL& url) const OVERRIDE;
 
   virtual bool HasInplaceCopyImplementation(
       fileapi::FileSystemType type) const OVERRIDE;
 
   virtual scoped_ptr<webkit_blob::FileStreamReader> CreateFileStreamReader(
       const fileapi::FileSystemURL& url,
       int64 offset,
+      int64 length,
       const base::Time& expected_modification_time,
       fileapi::FileSystemContext* context) const OVERRIDE;
 
   virtual scoped_ptr<fileapi::FileStreamWriter> CreateFileStreamWriter(
       const fileapi::FileSystemURL& url,
       int64 offset,
       fileapi::FileSystemContext* context) const OVERRIDE;
 
   virtual fileapi::FileSystemQuotaUtil* GetQuotaUtil() OVERRIDE;
 
  private:
   // User mount points.
   scoped_refptr<fileapi::ExternalMountPoints> mount_points_;
   scoped_ptr<PrivetFileSystemAsyncUtil> async_util_;
 };
 
 }  // namespace local_discovery
 
 #endif  // CHROME_BROWSER_LOCAL_DISCOVERY_STORAGE_PRIVET_FILESYSTEM_BACKEND_H_