[scheduler] Add WakeupBudgetPool.

third_party/WebKit/Source/platform/scheduler/renderer/throttled_time_domain.h

Index: third_party/WebKit/Source/platform/scheduler/renderer/throttled_time_domain.h
diff --git a/third_party/WebKit/Source/platform/scheduler/renderer/throttled_time_domain.h b/third_party/WebKit/Source/platform/scheduler/renderer/throttled_time_domain.h
index 0cb0f87d40a70beaec6fb94666532117c756d129..3ddb0d2c383bcabfd0efa260abc0833d2379b15b 100644
--- a/third_party/WebKit/Source/platform/scheduler/renderer/throttled_time_domain.h
+++ b/third_party/WebKit/Source/platform/scheduler/renderer/throttled_time_domain.h
@@ -18,6 +18,8 @@ class PLATFORM_EXPORT ThrottledTimeDomain : public RealTimeDomain {
   ThrottledTimeDomain();
   ~ThrottledTimeDomain() override;
 
+  void SetNextTaskRunTime(base::TimeTicks run_time);
+
   // TimeDomain implementation:
   const char* GetName() const override;
   void RequestWakeUpAt(base::TimeTicks now, base::TimeTicks run_time) override;
@@ -27,6 +29,10 @@ class PLATFORM_EXPORT ThrottledTimeDomain : public RealTimeDomain {
   using TimeDomain::WakeUpReadyDelayedQueues;
 
  private:
+  // Next task run time provided by task queue throttler. Note that it does not
+  // get reset, so it is valid only when in the future.
+  base::Optional<base::TimeTicks> next_task_run_time_;
+
   DISALLOW_COPY_AND_ASSIGN(ThrottledTimeDomain);
 };