[Reland] Make canceling Timers fast.

third_party/WebKit/Source/platform/scheduler/base/time_domain.cc

Index: third_party/WebKit/Source/platform/scheduler/base/time_domain.cc
diff --git a/third_party/WebKit/Source/platform/scheduler/base/time_domain.cc b/third_party/WebKit/Source/platform/scheduler/base/time_domain.cc
index 5837384e776dbb4f8e12d192a063927f9f2c2550..3093132d23a9c932bd99b8be8d4787800dfeca79 100644
--- a/third_party/WebKit/Source/platform/scheduler/base/time_domain.cc
+++ b/third_party/WebKit/Source/platform/scheduler/base/time_domain.cc
@@ -159,14 +159,16 @@ void TimeDomain::UpdateWorkQueues(LazyNow lazy_now) {
 
   MoveNewlyUpdatableQueuesIntoUpdatableQueueSet();
 
-  auto iter = updatable_queue_set_.begin();
+  std::set<internal::TaskQueueImpl*>::iterator iter =
+      updatable_queue_set_.begin();
   while (iter != updatable_queue_set_.end()) {
-    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();
+    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);
   }
 }
 
@@ -196,7 +198,7 @@ void TimeDomain::WakeupReadyDelayedQueues(LazyNow* lazy_now) {
     // 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->UpdateDelayedWorkQueue(lazy_now);
+      next_wakeup->second->MoveReadyDelayedTasksToDelayedWorkQueue(lazy_now);
     }
     delayed_wakeup_multimap_.erase(next_wakeup);
   }