Prevent redundant DoWorks due to canceled delayed tasks (v2)

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

 // Copyright 2015 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/throttling_helper.h"
 
 #include "base/logging.h"
 #include "platform/scheduler/base/real_time_domain.h"
 #include "platform/scheduler/child/scheduler_tqm_delegate.h"
 #include "platform/scheduler/renderer/auto_advancing_virtual_time_domain.h"
@@ skipping 128 matching lines @@
   DCHECK(has_delayed_task);
   base::TimeTicks now = tick_clock_->NowTicks();
   MaybeSchedulePumpThrottledTasksLocked(FROM_HERE, now,
                                         next_scheduled_delayed_task);
 }
 
 void ThrottlingHelper::PumpThrottledTasks() {
   TRACE_EVENT0(tracing_category_, "ThrottlingHelper::PumpThrottledTasks");
   pending_pump_throttled_tasks_runtime_ = base::TimeTicks();
 
-  LazyNow lazy_low(tick_clock_);
   for (const TaskQueueMap::value_type& map_entry : throttled_queues_) {
     TaskQueue* task_queue = map_entry.first;
     if (!map_entry.second.enabled || task_queue->IsEmpty())
       continue;
 
     task_queue->SetQueueEnabled(true);
     task_queue->InsertFence();
   }
-  // Make sure NextScheduledRunTime gives us an up-to date result.
-  time_domain_->ClearExpiredWakeups();
 
   base::TimeTicks next_scheduled_delayed_task;
   // Maybe schedule a call to ThrottlingHelper::PumpThrottledTasks if there is
   // a pending delayed task. NOTE posting a non-delayed task in the future will
   // result in ThrottlingHelper::OnTimeDomainHasImmediateWork being called.
   if (time_domain_->NextScheduledRunTime(&next_scheduled_delayed_task)) {
-    MaybeSchedulePumpThrottledTasksLocked(FROM_HERE, lazy_low.Now(),
+    LazyNow lazy_now(tick_clock_);
+    MaybeSchedulePumpThrottledTasksLocked(FROM_HERE, lazy_now.Now(),
                                           next_scheduled_delayed_task);
   }
 }
 
 /* static */
 base::TimeTicks ThrottlingHelper::ThrottledRunTime(
     base::TimeTicks unthrottled_runtime) {
   const base::TimeDelta one_second = base::TimeDelta::FromSeconds(1);
   return unthrottled_runtime + one_second -
          ((unthrottled_runtime - base::TimeTicks()) % one_second);
@@ skipping 39 matching lines @@
     throttled_queues_.erase(throttled_queues_.begin());
 
     task_queue->SetTimeDomain(renderer_scheduler_->GetVirtualTimeDomain());
     task_queue->RemoveFence();
     task_queue->SetQueueEnabled(enabled);
   }
 }
 
 }  // namespace scheduler
 }  // namespace blink