Move throttling of background timers into the renderer scheduler

components/scheduler/base/time_domain.h

Index: components/scheduler/base/time_domain.h
diff --git a/components/scheduler/base/time_domain.h b/components/scheduler/base/time_domain.h
index 476a68eb5f4299f78b66d2b069fef24320a1b37a..5cf39b709d11c09c47564c78a3f849565f6e7430 100644
--- a/components/scheduler/base/time_domain.h
+++ b/components/scheduler/base/time_domain.h
@@ -23,9 +23,24 @@ class TaskQueueImpl;
 class TaskQueueManager;
 class TaskQueueManagerDelegate;
 
-class SCHEDULER_EXPORT TimeDomain : public base::RefCounted<TimeDomain> {
+class SCHEDULER_EXPORT TimeDomain {
  public:
-  TimeDomain();
+  class SCHEDULER_EXPORT Observer {
+   public:
+    virtual ~Observer() {}
+
+    // Called when an empty TaskQueue registered with this TimeDomain has a task
+    // enqueued.
+    virtual void OnTimeDomainHasImmediateWork() = 0;
+
+    // Called when a TaskQueue registered with this TimeDomain has a delayed
+    // task enqueued and no other delayed tasks associated with this TimeDomain
+    // are pending.
+    virtual void OnTimeDomainHasDelayedWork() = 0;
+  };
+
+  explicit TimeDomain(Observer* observer);
+  virtual ~TimeDomain();
 
   // Returns a LazyNow that evaluate this TimeDomain's Now.  Can be called from
   // any thread.
@@ -46,9 +61,6 @@ class SCHEDULER_EXPORT TimeDomain : public base::RefCounted<TimeDomain> {
  protected:
   friend class internal::TaskQueueImpl;
   friend class TaskQueueManager;
-  friend class base::RefCounted<TimeDomain>;
-
-  virtual ~TimeDomain();
 
   void AsValueInto(base::trace_event::TracedValue* state) const;
 
@@ -70,6 +82,9 @@ class SCHEDULER_EXPORT TimeDomain : public base::RefCounted<TimeDomain> {
                            base::TimeTicks delayed_run_time,
                            LazyNow* lazy_now);
 
+  // Registers the |queue|.
+  void RegisterQueue(internal::TaskQueueImpl* queue);
+
   // Removes |queue| from the set of task queues that UpdateWorkQueues calls
   // UpdateWorkQueue on.
   void UnregisterAsUpdatableTaskQueue(internal::TaskQueueImpl* queue);
@@ -115,6 +130,10 @@ class SCHEDULER_EXPORT TimeDomain : public base::RefCounted<TimeDomain> {
   // only be accessed from the main thread.
   std::set<internal::TaskQueueImpl*> updatable_queue_set_;
 
+  std::set<internal::TaskQueueImpl*> registered_task_queues_;
+
+  Observer* observer_;
+
   base::ThreadChecker main_thread_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(TimeDomain);