Implement SequencedTaskChecker.

webrtc/base/base.gyp

 # Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
 #
 # Use of this source code is governed by a BSD-style license
 # that can be found in the LICENSE file in the root of the source
 # tree. An additional intellectual property rights grant can be found
 # in the file PATENTS.  All contributing project authors may
 # be found in the AUTHORS file in the root of the source tree.
 
 {
   'includes': [ '../build/common.gypi', ],
@@ skipping 118 matching lines @@
         }], # OS=="mac" and build_with_chromium==0
       ],
     },
     {
       'target_name': 'rtc_task_queue',
       'type': 'static_library',
       'dependencies': [
         'rtc_base_approved',
       ],
       'sources': [
+        'sequenced_task_checker.h',
+        'sequenced_task_checker_impl.cc',
+        'sequenced_task_checker_impl.h',
         'task_queue.h',
         'task_queue_posix.h',
       ],
       'conditions': [
         ['build_libevent==1', {
           'dependencies': [
             '<(DEPTH)/base/third_party/libevent/libevent.gyp:libevent',
           ],
         }],
         ['enable_libevent==1', {
@@ skipping 494 matching lines @@
     },
     {
      'target_name': 'gtest_prod',
       'type': 'static_library',
       'sources': [
         'gtest_prod_util.h',
       ],
     },
   ],
 }