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

storage/browser/fileapi/file_system_url_request_job.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 "storage/browser/fileapi/file_system_url_request_job.h"
 
 #include <vector>
 
 #include "base/bind.h"
 #include "base/compiler_specific.h"
@@ skipping 63 matching lines @@
       base::Bind(&FileSystemURLRequestJob::StartAsync,
                  weak_factory_.GetWeakPtr()));
 }
 
 void FileSystemURLRequestJob::Kill() {
   reader_.reset();
   URLRequestJob::Kill();
   weak_factory_.InvalidateWeakPtrs();
 }
 
-bool FileSystemURLRequestJob::ReadRawData(net::IOBuffer* dest, int dest_size,
-                                          int *bytes_read) {
+bool FileSystemURLRequestJob::ReadRawData(net::IOBuffer* dest,
+                                          int dest_size,
+                                          int* bytes_read) {
   DCHECK_NE(dest_size, 0);
   DCHECK(bytes_read);
   DCHECK_GE(remaining_bytes_, 0);
 
   if (reader_.get() == NULL)
     return false;
 
   if (remaining_bytes_ < dest_size)
     dest_size = static_cast<int>(remaining_bytes_);
 
@@ skipping 114 matching lines @@
     NotifyHeadersComplete();
     return;
   }
 
   remaining_bytes_ = byte_range_.last_byte_position() -
                      byte_range_.first_byte_position() + 1;
   DCHECK_GE(remaining_bytes_, 0);
 
   DCHECK(!reader_.get());
   reader_ = file_system_context_->CreateFileStreamReader(
-      url_, byte_range_.first_byte_position(), base::Time());
+      url_, byte_range_.first_byte_position(), remaining_bytes_, base::Time());
 
   set_expected_content_size(remaining_bytes_);
   response_info_.reset(new net::HttpResponseInfo());
   response_info_->headers = CreateHttpResponseHeaders();
   NotifyHeadersComplete();
 }
 
 void FileSystemURLRequestJob::DidRead(int result) {
   if (result > 0)
     SetStatus(URLRequestStatus());  // Clear the IO_PENDING status
@@ skipping 23 matching lines @@
   }
 
   return false;
 }
 
 void FileSystemURLRequestJob::NotifyFailed(int rv) {
   NotifyDone(URLRequestStatus(URLRequestStatus::FAILED, rv));
 }
 
 }  // namespace storage