Move throttling of background timers into the renderer scheduler

components/scheduler/base/time_domain_unittest.cc

Index: components/scheduler/base/time_domain_unittest.cc
diff --git a/components/scheduler/base/time_domain_unittest.cc b/components/scheduler/base/time_domain_unittest.cc
index d41305ac58d372ce54dd2c2bec37735e2f1004d8..f000cb151bf50d0449f4cf0d97b4a303824663b1 100644
--- a/components/scheduler/base/time_domain_unittest.cc
+++ b/components/scheduler/base/time_domain_unittest.cc
@@ -20,7 +20,8 @@ namespace scheduler {
 class MockTimeDomain : public TimeDomain {
  public:
   MockTimeDomain()
-      : now_(base::TimeTicks() + base::TimeDelta::FromSeconds(1)) {}
+      : TimeDomain(nullptr),
+        now_(base::TimeTicks() + base::TimeDelta::FromSeconds(1)) {}
 
   using TimeDomain::NextScheduledRunTime;
   using TimeDomain::NextScheduledTaskQueue;