Introduce a SchedulerHelper in content/child/scheduler

content/content_tests.gypi

Index: content/content_tests.gypi
diff --git a/content/content_tests.gypi b/content/content_tests.gypi
index c1e1dbf10d69c9c8c12c7fd9f52a48d17d187b25..86084e7304756f3a54194cb303f0bf5ba46f330a 100644
--- a/content/content_tests.gypi
+++ b/content/content_tests.gypi
@@ -580,6 +580,11 @@
       'child/notifications/notification_data_conversions_unittest.cc',
       'child/power_monitor_broadcast_source_unittest.cc',
       'child/resource_dispatcher_unittest.cc',
+      'child/scheduler/nestable_task_runner_for_test.cc',
+      'child/scheduler/nestable_task_runner_for_test.h',
+      'child/scheduler/prioritizing_task_queue_selector_unittest.cc',
+      'child/scheduler/scheduler_helper_unittest.cc',
+      'child/scheduler/task_queue_manager_unittest.cc',
       'child/service_worker/service_worker_dispatcher_unittest.cc',
       'child/simple_webmimeregistry_impl_unittest.cc',
       'child/site_isolation_policy_unittest.cc',
@@ -667,12 +672,8 @@
       'renderer/render_thread_impl_unittest.cc',
       'renderer/render_widget_unittest.cc',
       'renderer/scheduler/deadline_task_runner_unittest.cc',
-      'renderer/scheduler/nestable_task_runner_for_test.cc',
-      'renderer/scheduler/nestable_task_runner_for_test.h',
       'renderer/scheduler/renderer_scheduler_impl_unittest.cc',
-      'renderer/scheduler/renderer_task_queue_selector_unittest.cc',
       'renderer/scheduler/resource_dispatch_throttler_unittest.cc',
-      'renderer/scheduler/task_queue_manager_unittest.cc',
       'renderer/scheduler/webthread_impl_for_scheduler_unittest.cc',
       'renderer/screen_orientation/screen_orientation_dispatcher_unittest.cc',
       'renderer/skia_benchmarking_extension_unittest.cc',
@@ -1260,7 +1261,7 @@
             'browser/renderer_host/input/input_router_impl_perftest.cc',
             'common/cc_messages_perftest.cc',
             'common/discardable_shared_memory_heap_perftest.cc',
-            'renderer/scheduler/task_queue_manager_perftest.cc',
+            'child/scheduler/task_queue_manager_perftest.cc',
             'test/run_all_perftests.cc',
           ],
           'conditions': [