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

webkit/browser/fileapi/sandbox_file_system_backend.cc

 // Copyright (c) 2012 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 "webkit/browser/fileapi/sandbox_file_system_backend.h"
 
 #include "base/bind.h"
 #include "base/file_util.h"
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
@@ skipping 114 matching lines @@
 
 bool SandboxFileSystemBackend::HasInplaceCopyImplementation(
     fileapi::FileSystemType type) const {
   return true;
 }
 
 scoped_ptr<webkit_blob::FileStreamReader>
 SandboxFileSystemBackend::CreateFileStreamReader(
     const FileSystemURL& url,
     int64 offset,
+    int64 length,
     const base::Time& expected_modification_time,
     FileSystemContext* context) const {
   DCHECK(CanHandleType(url.type()));
   DCHECK(delegate_);
   return delegate_->CreateFileStreamReader(
       url, offset, expected_modification_time, context);
 }
 
 scoped_ptr<fileapi::FileStreamWriter>
 SandboxFileSystemBackend::CreateFileStreamWriter(
     const FileSystemURL& url,
     int64 offset,
     FileSystemContext* context) const {
   DCHECK(CanHandleType(url.type()));
   DCHECK(delegate_);
   return delegate_->CreateFileStreamWriter(url, offset, context, url.type());
 }
 
 FileSystemQuotaUtil* SandboxFileSystemBackend::GetQuotaUtil() {
   return delegate_;
 }
 
 SandboxFileSystemBackendDelegate::OriginEnumerator*
 SandboxFileSystemBackend::CreateOriginEnumerator() {
   DCHECK(delegate_);
   return delegate_->CreateOriginEnumerator();
 }
 
 }  // namespace fileapi