Implement async verision of FileSystemFileUtil and in-memory file system for testing purposes.

webkit/fileapi/webkit_fileapi.gypi

 # Copyright (c) 2011 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.
 
 {
   'targets': [
     {
       'target_name': 'fileapi',
       'type': 'static_library',
       'variables': { 'enable_wexit_time_destructors': 1, },
@@ skipping 54 matching lines @@
         'webfilewriter_base.h',
       ],
       'conditions': [
         ['inside_chromium_build==0', {
           'dependencies': [
             '<(DEPTH)/webkit/support/setup_third_party.gyp:third_party_headers',
           ],
         }],
         ['chromeos==1', {
           'sources': [
+            '../chromeos/fileapi/async_file_stream.h',
             '../chromeos/fileapi/cros_mount_point_provider.cc',
             '../chromeos/fileapi/cros_mount_point_provider.h',
             '../chromeos/fileapi/file_access_permissions.cc',
             '../chromeos/fileapi/file_access_permissions.h',
+            '../chromeos/fileapi/file_util_async.h',
           ],
         }],
       ],
     },
   ],
 }