[scheduler] Add WakeupBudgetPool.

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

Index: third_party/WebKit/Source/platform/scheduler/renderer/throttled_time_domain.cc
diff --git a/third_party/WebKit/Source/platform/scheduler/renderer/throttled_time_domain.cc b/third_party/WebKit/Source/platform/scheduler/renderer/throttled_time_domain.cc
index 9126c6f02e88f3329f04f6f29b801b5121cd0e5c..27eceea3ae0b4323919648ace6d9ec523b15f8d5 100644
--- a/third_party/WebKit/Source/platform/scheduler/renderer/throttled_time_domain.cc
+++ b/third_party/WebKit/Source/platform/scheduler/renderer/throttled_time_domain.cc
@@ -26,8 +26,15 @@ void ThrottledTimeDomain::CancelWakeUpAt(base::TimeTicks run_time) {
   // We ignore this because RequestWakeUpAt is a NOP.
 }
 
+void ThrottledTimeDomain::SetNextTask(base::TimeTicks run_time) {
+  next_task_ = run_time;
+}
+
 base::Optional<base::TimeDelta> ThrottledTimeDomain::DelayTillNextTask(
     LazyNow* lazy_now) {
+  if (next_task_ && next_task_ > lazy_now->Now())
+    return next_task_.value() - lazy_now->Now();
+
   base::TimeTicks next_run_time;
   if (!NextScheduledRunTime(&next_run_time))
     return base::nullopt;