Revert of Make canceling Timers fast.

third_party/WebKit/Source/platform/scheduler/base/time_domain.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/base/time_domain.h"
 
 #include <set>
 
 #include "platform/scheduler/base/task_queue_impl.h"
 #include "platform/scheduler/base/task_queue_manager_delegate.h"
@@ skipping 141 matching lines @@
 }
 
 void TimeDomain::UpdateWorkQueues(LazyNow lazy_now) {
   DCHECK(main_thread_checker_.CalledOnValidThread());
 
   // Move any ready delayed tasks into the Incoming queues.
   WakeupReadyDelayedQueues(&lazy_now);
 
   MoveNewlyUpdatableQueuesIntoUpdatableQueueSet();
 
-  std::set<internal::TaskQueueImpl*>::iterator iter =
-      updatable_queue_set_.begin();
+  auto iter = updatable_queue_set_.begin();
   while (iter != updatable_queue_set_.end()) {
-    std::set<internal::TaskQueueImpl*>::iterator queue_it = iter++;
-    internal::TaskQueueImpl* queue = *queue_it;
-
-    // Update the queue and remove from the set if subsequent updates are not
-    // required.
-    if (!queue->MaybeUpdateImmediateWorkQueues())
-      updatable_queue_set_.erase(queue_it);
+    internal::TaskQueueImpl* queue = *iter++;
+    // NOTE Update work queue may erase itself from |updatable_queue_set_|.
+    // This is fine, erasing an element won't invalidate any interator, as long
+    // as the iterator isn't the element being delated.
+    if (queue->immediate_work_queue()->Empty())
+      queue->UpdateImmediateWorkQueue();
   }
 }
 
 void TimeDomain::MoveNewlyUpdatableQueuesIntoUpdatableQueueSet() {
   DCHECK(main_thread_checker_.CalledOnValidThread());
   base::AutoLock lock(newly_updatable_lock_);
   while (!newly_updatable_.empty()) {
     updatable_queue_set_.insert(newly_updatable_.back());
     newly_updatable_.pop_back();
   }
 }
 
 void TimeDomain::WakeupReadyDelayedQueues(LazyNow* lazy_now) {
   DCHECK(main_thread_checker_.CalledOnValidThread());
   // Wake up any queues with pending delayed work.  Note std::multipmap stores
   // the elements sorted by key, so the begin() iterator points to the earliest
   // queue to wakeup.
   std::set<internal::TaskQueueImpl*> dedup_set;
   while (!delayed_wakeup_multimap_.empty()) {
     DelayedWakeupMultimap::iterator next_wakeup =
         delayed_wakeup_multimap_.begin();
     if (next_wakeup->first > lazy_now->Now())
       break;
     // A queue could have any number of delayed tasks pending so it's worthwhile
     // deduping calls to UpdateDelayedWorkQueue since it takes a lock.
     // NOTE the order in which these are called matters since the order
     // in which EnqueueTaskLocks is called is respected when choosing which
     // queue to execute a task from.
     if (dedup_set.insert(next_wakeup->second).second) {
-      next_wakeup->second->MoveReadyDelayedTasksToDelayedWorkQueue(lazy_now);
+      next_wakeup->second->UpdateDelayedWorkQueue(lazy_now);
     }
     delayed_wakeup_multimap_.erase(next_wakeup);
   }
 }
 
 void TimeDomain::ClearExpiredWakeups() {
   DCHECK(main_thread_checker_.CalledOnValidThread());
   LazyNow lazy_now(CreateLazyNow());
   while (!delayed_wakeup_multimap_.empty()) {
     DelayedWakeupMultimap::iterator next_wakeup =
@@ skipping 33 matching lines @@
   if (!delayed_wakeup_multimap_.empty()) {
     base::TimeDelta delay = delayed_wakeup_multimap_.begin()->first - Now();
     state->SetDouble("next_delay_ms", delay.InMillisecondsF());
   }
   AsValueIntoInternal(state);
   state->EndDictionary();
 }
 
 }  // namespace scheduler
 }  // namespace blink