Introduce a SchedulerHelper in content/child/scheduler

content/content_child.gypi

 # Copyright 2013 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.
 
 {
   'dependencies': [
     '../base/base.gyp:base',
     '../components/tracing.gyp:tracing',
     '../mojo/mojo_base.gyp:mojo_environment_chromium',
     '../mojo/mojo_base.gyp:mojo_common_lib',
@@ skipping 168 matching lines @@
       'child/push_messaging/push_provider.cc',
       'child/push_messaging/push_provider.h',
       'child/quota_dispatcher.cc',
       'child/quota_dispatcher.h',
       'child/quota_message_filter.cc',
       'child/quota_message_filter.h',
       'child/request_extra_data.cc',
       'child/request_extra_data.h',
       'child/request_info.cc',
       'child/request_info.h',
+      'child/scheduler/cancelable_closure_holder.cc',
+      'child/scheduler/cancelable_closure_holder.h',
+      'child/scheduler/nestable_single_thread_task_runner.h',
+      'child/scheduler/null_idle_task_runner.cc',
+      'child/scheduler/null_idle_task_runner.h',
+      'child/scheduler/prioritizing_task_queue_selector.cc',
+      'child/scheduler/prioritizing_task_queue_selector.h',
+      'child/scheduler/scheduler_helper.cc',
+      'child/scheduler/scheduler_helper.h',
+      'child/scheduler/scheduler_message_loop_delegate.cc',
+      'child/scheduler/scheduler_message_loop_delegate.h',
+      'child/scheduler/single_thread_idle_task_runner.cc',
+      'child/scheduler/single_thread_idle_task_runner.h',
+      'child/scheduler/task_queue_selector.h',
+      'child/scheduler/task_queue_manager.cc',
+      'child/scheduler/task_queue_manager.h',
       'child/resource_dispatcher.cc',
       'child/resource_dispatcher.h',
       'child/resource_scheduling_filter.cc',
       'child/resource_scheduling_filter.h',
       'child/runtime_features.cc',
       'child/runtime_features.h',
       'child/scoped_child_process_reference.cc',
       'child/scoped_child_process_reference.h',
       'child/service_worker/service_worker_dispatcher.cc',
       'child/service_worker/service_worker_dispatcher.h',
@@ skipping 203 matching lines @@
         }, {
           'dependencies': [
             '../third_party/nss/nss.gyp:nspr',
             '../third_party/nss/nss.gyp:nss',
           ],
         }],
       ],
     }],
   ],
 }