Added --force-ui-direction flag for developers to force LTR or RTL.

base/base.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.
 
 {
   'includes': [
     'trace_event/trace_event.gypi',
   ],
   'target_defaults': {
     'variables': {
@@ skipping 1000 matching lines @@
             'defines': ['SYSTEM_NATIVE_UTF8'],
           }],
         ],
       }],
       ['base_i18n_target==1', {
         'defines': [
           'BASE_I18N_IMPLEMENTATION',
         ],
         'sources': [
           'i18n/base_i18n_export.h',
+          'i18n/base_i18n_switches.cc',
+          'i18n/base_i18n_switches.h',
           'i18n/bidi_line_iterator.cc',
           'i18n/bidi_line_iterator.h',
           'i18n/break_iterator.cc',
           'i18n/break_iterator.h',
           'i18n/case_conversion.cc',
           'i18n/case_conversion.h',
           'i18n/char_iterator.cc',
           'i18n/char_iterator.h',
           'i18n/file_util_icu.cc',
           'i18n/file_util_icu.h',
@@ skipping 21 matching lines @@
           'i18n/time_formatting.h',
           'i18n/timezone.cc',
           'i18n/timezone.h',
           'i18n/utf8_validator_tables.cc',
           'i18n/utf8_validator_tables.h',
         ],
       }]
     ],
   },
 }