[fsp] Buffer consecutive Write() calls.

chrome/chrome_tests_unit.gypi

 # Copyright 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': {
     'chrome_unit_tests_sources': [
       '../apps/saved_files_service_unittest.cc',
       '../components/autofill/content/renderer/test_password_autofill_agent.cc',
       '../components/autofill/content/renderer/test_password_autofill_agent.h',
       '../components/autofill/content/renderer/test_password_generation_agent.cc',
@@ skipping 132 matching lines @@
       'browser/chromeos/extensions/wallpaper_private_api_unittest.cc',
       'browser/chromeos/external_metrics_unittest.cc',
       'browser/chromeos/file_manager/file_tasks_unittest.cc',
       'browser/chromeos/file_manager/file_watcher_unittest.cc',
       'browser/chromeos/file_manager/path_util_unittest.cc',
       'browser/chromeos/file_manager/url_util_unittest.cc',
       'browser/chromeos/file_manager/volume_manager_unittest.cc',
       'browser/chromeos/file_system_provider/fake_provided_file_system.cc',
       'browser/chromeos/file_system_provider/fake_provided_file_system.h',
       'browser/chromeos/file_system_provider/fileapi/buffering_file_stream_reader_unittest.cc',
+      'browser/chromeos/file_system_provider/fileapi/buffering_file_stream_writer_unittest.cc',
       'browser/chromeos/file_system_provider/fileapi/file_stream_reader_unittest.cc',
       'browser/chromeos/file_system_provider/fileapi/file_stream_writer_unittest.cc',
       'browser/chromeos/file_system_provider/fileapi/provider_async_file_util_unittest.cc',
       'browser/chromeos/file_system_provider/mount_path_util_unittest.cc',
       'browser/chromeos/file_system_provider/operations/abort_unittest.cc',
       'browser/chromeos/file_system_provider/operations/close_file_unittest.cc',
       'browser/chromeos/file_system_provider/operations/copy_entry_unittest.cc',
       'browser/chromeos/file_system_provider/operations/create_directory_unittest.cc',
       'browser/chromeos/file_system_provider/operations/create_file_unittest.cc',
       'browser/chromeos/file_system_provider/operations/delete_entry_unittest.cc',
@@ skipping 2703 matching lines @@
               'dependencies': [
                 '../tools/xdisplaycheck/xdisplaycheck.gyp:xdisplaycheck',
               ],
             }],
           ],
         },
       ],
     }],
   ],  # 'conditions'
 }