Adds a flag to support "Virtual Time" to the blink scheduler

components/scheduler/scheduler.gypi

Index: components/scheduler/scheduler.gypi
diff --git a/components/scheduler/scheduler.gypi b/components/scheduler/scheduler.gypi
index d285e45723601d64a2bc5abe3a257aeb322bf7dd..208d110284d456efe8f8a506ecd59962064c690c 100644
--- a/components/scheduler/scheduler.gypi
+++ b/components/scheduler/scheduler.gypi
@@ -4,18 +4,22 @@
 
 {
   'variables': {
+    'scheduler_common_sources': [
+      'common/scheduler_switches.cc',
+      'common/scheduler_switches.h',
+    ],
     'scheduler_sources': [
       'base/cancelable_closure_holder.cc',
       'base/cancelable_closure_holder.h',
       'base/lazy_now.cc',
       'base/lazy_now.h',
-      'base/nestable_single_thread_task_runner.h',
       'base/task_queue.cc',
       'base/task_queue.h',
       'base/task_queue_impl.cc',
       'base/task_queue_impl.h',
       'base/task_queue_manager.cc',
       'base/task_queue_manager.h',
+      'base/task_queue_manager_delegate.h',
       'base/task_queue_selector.cc',
       'base/task_queue_selector.h',
       'base/task_queue_sets.cc',
@@ -27,11 +31,13 @@
       'child/idle_helper.h',
       'child/scheduler_helper.cc',
       'child/scheduler_helper.h',
-      'child/scheduler_task_runner_delegate.h',
-      'child/scheduler_task_runner_delegate_impl.cc',
-      'child/scheduler_task_runner_delegate_impl.h',
+      'child/scheduler_tqm_delegate.h',
+      'child/scheduler_tqm_delegate_impl.cc',
+      'child/scheduler_tqm_delegate_impl.h',
       'child/single_thread_idle_task_runner.cc',
       'child/single_thread_idle_task_runner.h',
+      'child/virtual_time_tqm_delegate.cc',
+      'child/virtual_time_tqm_delegate.h',
       'child/web_scheduler_impl.cc',
       'child/web_scheduler_impl.h',
       'child/web_task_runner_impl.cc',