Make FileStream::Seek async and add FileStream::SeekSync for sync operation

webkit/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/fileapi/file_system_url_request_job.h"
 
 #include "base/bind.h"
 #include "base/compiler_specific.h"
 #include "base/file_path.h"
 #include "base/file_util_proxy.h"
@@ skipping 225 matching lines @@
                      byte_range_.first_byte_position() + 1;
   DCHECK_GE(remaining_bytes_, 0);
 
   // TODO(adamk): Please remove this ScopedAllowIO once we support async seek
   // on FileStream. crbug.com/113300
   base::ThreadRestrictions::ScopedAllowIO allow_io;
   // Do the seek at the beginning of the request.
   if (remaining_bytes_ > 0 &&
       byte_range_.first_byte_position() != 0 &&
       byte_range_.first_byte_position() !=
-          stream_->Seek(net::FROM_BEGIN, byte_range_.first_byte_position())) {
+          stream_->SeekSync(net::FROM_BEGIN,
+                            byte_range_.first_byte_position())) {
     NotifyFailed(net::ERR_REQUEST_RANGE_NOT_SATISFIABLE);
     return;
   }
 
   set_expected_content_size(remaining_bytes_);
   response_info_.reset(new net::HttpResponseInfo());
   response_info_->headers = CreateHttpResponseHeaders();
 
   NotifyHeadersComplete();
 }
@@ skipping 27 matching lines @@
   }
 
   return false;
 }
 
 void FileSystemURLRequestJob::NotifyFailed(int rv) {
   NotifyDone(URLRequestStatus(URLRequestStatus::FAILED, rv));
 }
 
 }  // namespace fileapi