Make MediaFileUtil run on thread pool.

webkit/fileapi/file_system_file_stream_reader.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_file_stream_reader.h"
 
 #include "base/file_util_proxy.h"
 #include "base/platform_file.h"
-#include "base/sequenced_task_runner.h"
+#include "base/single_thread_task_runner.h"
 #include "net/base/file_stream.h"
 #include "net/base/io_buffer.h"
 #include "net/base/net_errors.h"
 #include "webkit/blob/local_file_stream_reader.h"
 #include "webkit/fileapi/file_system_context.h"
 #include "webkit/fileapi/file_system_operation_interface.h"
+#include "webkit/fileapi/file_system_task_runners.h"
 
 using webkit_blob::LocalFileStreamReader;
 
 namespace fileapi {
 
 namespace {
 
 void ReadAdapter(base::WeakPtr<FileSystemFileStreamReader> reader,
                  net::IOBuffer* buf, int buf_len,
                  const net::CompletionCallback& callback) {
   if (!reader.get())
     return;
   int rv = reader->Read(buf, buf_len, callback);
   if (rv != net::ERR_IO_PENDING)
     callback.Run(rv);
 }
 
-}
+}  // namespace
 
 FileSystemFileStreamReader::FileSystemFileStreamReader(
     FileSystemContext* file_system_context,
     const FileSystemURL& url,
     int64 initial_offset)
     : file_system_context_(file_system_context),
       url_(url),
       initial_offset_(initial_offset),
       has_pending_create_snapshot_(false),
       weak_factory_(ALLOW_THIS_IN_INITIALIZER_LIST(this)) {
@@ skipping 36 matching lines @@
 
   if (file_error != base::PLATFORM_FILE_OK) {
     callback.Run(net::PlatformFileErrorToNetError(file_error));
     return;
   }
 
   // Keep the reference (if it's non-null) so that the file won't go away.
   snapshot_ref_ = file_ref;
 
   local_file_reader_.reset(
-      new LocalFileStreamReader(file_system_context_->file_task_runner(),
-                                platform_path,
-                                initial_offset_,
-                                base::Time()));
+      new LocalFileStreamReader(
+          file_system_context_->task_runners()->file_task_runner(),
+          platform_path, initial_offset_, base::Time()));
 
   read_closure.Run();
 }
 
 }  // namespace fileapi