[scheduler] Add WakeupBudgetPool.

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

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "platform/scheduler/renderer/throttled_time_domain.h"
 
 namespace blink {
 namespace scheduler {
 
 ThrottledTimeDomain::ThrottledTimeDomain(const char* tracing_category)
     : RealTimeDomain(tracing_category) {}
 
 ThrottledTimeDomain::~ThrottledTimeDomain() {}
 
 const char* ThrottledTimeDomain::GetName() const {
   return "ThrottledTimeDomain";
 }
 
 void ThrottledTimeDomain::RequestWakeUpAt(base::TimeTicks now,
                                           base::TimeTicks run_time) {
   // We assume the owner (i.e. TaskQueueThrottler) will manage wake-ups on our
   // behalf.
 }
 
 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;
 
   base::TimeTicks now = lazy_now->Now();
   if (now >= next_run_time)
     return base::TimeDelta();  // Makes DoWork post an immediate continuation.
 
   // We assume the owner (i.e. TaskQueueThrottler) will manage wake-ups on our
   // behalf.
   return base::nullopt;
 }
 
 }  // namespace scheduler
 }  // namespace blink