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..1f58150bdffc73674003840c28d1ea464b6ea7db 100644
--- a/components/scheduler/base/time_domain.h
+++ b/components/scheduler/base/time_domain.h
@@ -43,6 +43,20 @@ class SCHEDULER_EXPORT TimeDomain : public base::RefCounted<TimeDomain> {
   // runtime for the next one and it returns true.  Returns false otherwise.
   bool NextScheduledRunTime(base::TimeTicks* out_time) const;
 
+  class SCHEDULER_EXPORT Observer {
+   public:
+    virtual ~Observer() {}
+
+    // Called when RegisterAsUpdatableTaskQueue is called. Can fire from any
+    // thread.
+    virtual void OnRegisterAsUpdatableTaskQueue() = 0;

[Sami, 2015/11/24 12:48:48]

How about OnHasNewWork, OnNewIncomingWork, OnNewImmediateWork or something like
that? I think the registration business is really an implementation detail.

Another idea:

OnTimeDomainHasImmediateWork()
OnTimeDomainHasDelayedWork()

[alex clarke (OOO till 29th), 2015/11/25 12:29:36]

Done.

+
+    // Called when RequestWakeup is called. Called only from the main thread.
+    virtual void OnRequestWakeup() = 0;
+  };
+
+  void SetObserver(Observer* observer);
+
  protected:
   friend class internal::TaskQueueImpl;
   friend class TaskQueueManager;
@@ -115,6 +129,8 @@ class SCHEDULER_EXPORT TimeDomain : public base::RefCounted<TimeDomain> {
   // only be accessed from the main thread.
   std::set<internal::TaskQueueImpl*> updatable_queue_set_;
 
+  Observer* observer_;
+
   base::ThreadChecker main_thread_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(TimeDomain);