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

webkit/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 "webkit/browser/fileapi/file_system_url_request_job.h"
 
 #include <vector>
 
 #include "base/bind.h"
 #include "base/compiler_specific.h"
@@ skipping 199 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(),
+      byte_range_.last_byte_position() - byte_range_.first_byte_position() + 1,

[hashimoto, 2014/08/22 06:53:42]

You can use remaining_bytes_.

[mtomasz, 2014/08/25 03:32:31]

Done.

+      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 fileapi