[fsp] Buffer consecutive Write() calls.

chrome/chrome_browser_chromeos.gypi

 # 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.
 
 {
   'variables': {
     # These files lists are shared with the GN build.
     'browser_chromeos_sources': [
         # All .cc, .h, .m, and .mm files under browser/chromeos, except for tests
@@ skipping 251 matching lines @@
         'browser/chromeos/file_manager/volume_manager.h',
         'browser/chromeos/file_manager/volume_manager_factory.cc',
         'browser/chromeos/file_manager/volume_manager_factory.h',
         'browser/chromeos/file_manager/volume_manager_observer.h',
         'browser/chromeos/file_manager/zip_file_creator.cc',
         'browser/chromeos/file_manager/zip_file_creator.h',
         'browser/chromeos/file_system_provider/fileapi/backend_delegate.cc',
         'browser/chromeos/file_system_provider/fileapi/backend_delegate.h',
         'browser/chromeos/file_system_provider/fileapi/buffering_file_stream_reader.cc',
         'browser/chromeos/file_system_provider/fileapi/buffering_file_stream_reader.h',
+        'browser/chromeos/file_system_provider/fileapi/buffering_file_stream_writer.cc',
+        'browser/chromeos/file_system_provider/fileapi/buffering_file_stream_writer.h',
         'browser/chromeos/file_system_provider/fileapi/file_stream_reader.cc',
         'browser/chromeos/file_system_provider/fileapi/file_stream_reader.h',
         'browser/chromeos/file_system_provider/fileapi/file_stream_writer.cc',
         'browser/chromeos/file_system_provider/fileapi/file_stream_writer.h',
         'browser/chromeos/file_system_provider/fileapi/provider_async_file_util.cc',
         'browser/chromeos/file_system_provider/fileapi/provider_async_file_util.h',
         'browser/chromeos/file_system_provider/mount_path_util.cc',
         'browser/chromeos/file_system_provider/mount_path_util.h',
         'browser/chromeos/file_system_provider/notification_manager.cc',
         'browser/chromeos/file_system_provider/notification_manager.h',
@@ skipping 959 matching lines @@
         'browser/chromeos/attestation/attestation_signed_data.proto',
       ],
       'variables': {
         'proto_in_dir': 'browser/chromeos/attestation',
         'proto_out_dir': 'chrome/browser/chromeos/attestation',
       },
       'includes': [ '../build/protoc.gypi' ]
     },
   ],
 }