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..3bf7b61aa5e30de69d2c279a40d70b6694c81f8a 100644
--- a/components/scheduler/base/time_domain.h
+++ b/components/scheduler/base/time_domain.h
@@ -25,7 +25,19 @@ class TaskQueueManagerDelegate;
 
 class SCHEDULER_EXPORT TimeDomain : public base::RefCounted<TimeDomain> {
  public:
-  TimeDomain();
+  class SCHEDULER_EXPORT Observer {
+   public:
+    virtual ~Observer() {}
+
+    // Called when RegisterAsUpdatableTaskQueue is called. Can fire from any

[Sami, 2015/11/25 17:12:25]

nit: these two comments don't really make sense unless you know how TimeDomain
works internally. Maybe just describe them more generally?

[alex clarke (OOO till 29th), 2015/11/26 18:43:27]

Done.

+    // thread.
+    virtual void OnTimeDomainHasImmediateWork() = 0;
+
+    // Called when RequestWakeup is called. Called only from the main thread.
+    virtual void OnTimeDomainHasDelayedWork() = 0;
+  };
+
+  explicit TimeDomain(Observer* observer);
 
   // Returns a LazyNow that evaluate this TimeDomain's Now.  Can be called from
   // any thread.
@@ -115,6 +127,8 @@ 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);