Move throttling of background timers into the renderer scheduler

components/scheduler/base/virtual_time_domain.h

Index: components/scheduler/base/virtual_time_domain.h
diff --git a/components/scheduler/base/virtual_time_domain.h b/components/scheduler/base/virtual_time_domain.h
index ce1f99aac1b1896b5861718ff39ccb3697008c37..78239c1c26dc780234c1b93a55db4bc65a6c2409 100644
--- a/components/scheduler/base/virtual_time_domain.h
+++ b/components/scheduler/base/virtual_time_domain.h
@@ -15,7 +15,9 @@ class TaskQueueManagerDelegate;
 
 class SCHEDULER_EXPORT VirtualTimeDomain : public TimeDomain {
  public:
-  VirtualTimeDomain(base::TimeTicks initial_time);
+  VirtualTimeDomain(TimeDomain::Observer* observer,
+                    base::TimeTicks initial_time);
+  ~VirtualTimeDomain() override;
 
   // TimeDomain implementation:
   LazyNow CreateLazyNow() override;
@@ -41,8 +43,6 @@ class SCHEDULER_EXPORT VirtualTimeDomain : public TimeDomain {
   TaskQueueManagerDelegate* task_queue_manager_delegate_;  // NOT OWNED
   base::Closure do_work_closure_;
 
-  ~VirtualTimeDomain() override;
-
   DISALLOW_COPY_AND_ASSIGN(VirtualTimeDomain);
 };