TaskScheduler: Delegate instead of callbacks for SchedulerWorkerThread.

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 626 matching lines @@
           'task_runner.cc',
           'task_runner.h',
           'task_runner_util.h',
           'task_scheduler/priority_queue.cc',
           'task_scheduler/priority_queue.h',
           'task_scheduler/scheduler_lock.h',
           'task_scheduler/scheduler_lock_impl.cc',
           'task_scheduler/scheduler_lock_impl.h',
           'task_scheduler/scheduler_worker_thread.cc',
           'task_scheduler/scheduler_worker_thread.h',
+          'task_scheduler/scheduler_worker_thread_delegate.h',
           'task_scheduler/sequence.cc',
           'task_scheduler/sequence.h',
           'task_scheduler/sequence_sort_key.cc',
           'task_scheduler/sequence_sort_key.h',
           'task_scheduler/task.cc',
           'task_scheduler/task.h',
           'task_scheduler/task_tracker.cc',
           'task_scheduler/task_tracker.h',
           'task_scheduler/task_traits.cc',
           'task_scheduler/task_traits.h',
@@ skipping 425 matching lines @@
           'i18n/time_formatting.h',
           'i18n/timezone.cc',
           'i18n/timezone.h',
           'i18n/utf8_validator_tables.cc',
           'i18n/utf8_validator_tables.h',
         ],
       }]
     ],
   },
 }