Create a reader-writer lock implementaiton in base.

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 592 matching lines @@
           'synchronization/cancellation_flag.cc',
           'synchronization/cancellation_flag.h',
           'synchronization/condition_variable.h',
           'synchronization/condition_variable_posix.cc',
           'synchronization/condition_variable_win.cc',
           'synchronization/lock.cc',
           'synchronization/lock.h',
           'synchronization/lock_impl.h',
           'synchronization/lock_impl_posix.cc',
           'synchronization/lock_impl_win.cc',
+          'synchronization/read_write_lock.h',
+          'synchronization/read_write_lock_nacl.cc',
+          'synchronization/read_write_lock_posix.cc',
+          'synchronization/read_write_lock_win.cc',
           'synchronization/spin_wait.h',
           'synchronization/waitable_event.h',
           'synchronization/waitable_event_posix.cc',
           'synchronization/waitable_event_watcher.h',
           'synchronization/waitable_event_watcher_posix.cc',
           'synchronization/waitable_event_watcher_win.cc',
           'synchronization/waitable_event_win.cc',
           'sys_byteorder.h',
           'sys_info.cc',
           'sys_info.h',
@@ skipping 247 matching lines @@
                'posix/unix_domain_socket_linux.cc',
                'process/kill.cc',
                'process/kill_posix.cc',
                'process/launch.cc',
                'process/launch_posix.cc',
                'process/process_metrics.cc',
                'process/process_metrics_posix.cc',
                'process/process_posix.cc',
                'rand_util_posix.cc',
                'scoped_native_library.cc',
+               'synchronization/read_write_lock_posix.cc',
                'sys_info.cc',
                'sys_info_posix.cc',
                'third_party/dynamic_annotations/dynamic_annotations.c',
             ],
             'sources/': [
               ['include', '^threading/platform_thread_linux\\.cc$'],
             ],
           }],
           ['OS == "android" and >(nacl_untrusted_build)==0', {
             'sources!': [
@@ skipping 207 matching lines @@
           'i18n/time_formatting.h',
           'i18n/timezone.cc',
           'i18n/timezone.h',
           'i18n/utf8_validator_tables.cc',
           'i18n/utf8_validator_tables.h',
         ],
       }]
     ],
   },
 }