[Try # 3] Scheduler refactoring to virtually eliminate redundant DoWorks

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(TimeDomain::Observer* observer,
                                          const char* tracing_category)
     : RealTimeDomain(observer, tracing_category) {}
 
 ThrottledTimeDomain::~ThrottledTimeDomain() {}
 
 const char* ThrottledTimeDomain::GetName() const {
   return "ThrottledTimeDomain";
 }
 
 void ThrottledTimeDomain::RequestWakeup(base::TimeTicks now,
                                         base::TimeDelta delay) {
   // We assume the owner (i.e. TaskQueueThrottler) will manage wakeups on our
   // behalf.
 }
 
-bool ThrottledTimeDomain::MaybeAdvanceTime() {
+base::Optional<base::TimeDelta> ThrottledTimeDomain::DelayTillNextTask(
+    LazyNow* lazy_now) {
   base::TimeTicks next_run_time;
   if (!NextScheduledRunTime(&next_run_time))
-    return false;
+    return base::Optional<base::TimeDelta>();
 
-  base::TimeTicks now = Now();
+  base::TimeTicks now = lazy_now->Now();
   if (now >= next_run_time)
-    return true;  // Causes DoWork to post a continuation.
+    return base::TimeDelta();  // Makes DoWork post an immediate continuation.
 
-  // Unlike RealTimeDomain::MaybeAdvanceTime we don't request a wake up here, we
-  // assume the owner (i.e. TaskQueueThrottler) will manage wakeups on our
+  // Unlike RealTimeDomain::ContinuationNeeded we don't request a wake up here,
+  // we assume the owner (i.e. TaskQueueThrottler) will manage wakeups on our
   // behalf.
-  return false;
+  return base::Optional<base::TimeDelta>();
 }
 
 }  // namespace scheduler
 }  // namespace blink