scheduler: Ensure consistent delayed task ordering between task queues

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 9f8c9090d0af9bdce51e8464aff14a6172545c08..5877f6b1f8347c46b1d27e17c86a71555e6dd826 100644
--- a/third_party/WebKit/Source/platform/scheduler/base/time_domain.cc
+++ b/third_party/WebKit/Source/platform/scheduler/base/time_domain.cc
@@ -33,6 +33,7 @@ void TimeDomain::UnregisterQueue(internal::TaskQueueImpl* queue) {
 
 void TimeDomain::ScheduleDelayedWork(internal::TaskQueueImpl* queue,
                                      base::TimeTicks delayed_run_time,
+                                     int sequence_num,
                                      base::TimeTicks now) {
   DCHECK(main_thread_checker_.CalledOnValidThread());
   DCHECK_EQ(queue->GetTimeDomain(), this);
@@ -44,10 +45,10 @@ void TimeDomain::ScheduleDelayedWork(internal::TaskQueueImpl* queue,
 
     // O(log n)
     delayed_wakeup_queue_.ChangeKey(queue->heap_handle(),
-                                    {delayed_run_time, queue});
+                                    {delayed_run_time, sequence_num, queue});
   } else {
     // O(log n)
-    delayed_wakeup_queue_.insert({delayed_run_time, queue});
+    delayed_wakeup_queue_.insert({delayed_run_time, sequence_num, queue});
   }
 
   queue->set_scheduled_time_domain_wakeup(delayed_run_time);
@@ -90,19 +91,22 @@ void TimeDomain::CancelDelayedWork(internal::TaskQueueImpl* queue) {
 
 void TimeDomain::WakeupReadyDelayedQueues(LazyNow* lazy_now) {
   DCHECK(main_thread_checker_.CalledOnValidThread());
-  // Wake up any queues with pending delayed work.  Note std::multipmap stores
+  // Wake up any queues with pending delayed work.  Note std::multimap stores
   // the elements sorted by key, so the begin() iterator points to the earliest
   // queue to wakeup.
   while (!delayed_wakeup_queue_.empty() &&
          delayed_wakeup_queue_.min().time <= lazy_now->Now()) {
     internal::TaskQueueImpl* queue = delayed_wakeup_queue_.min().queue;
-    base::Optional<base::TimeTicks> next_wakeup =
-        queue->WakeUpForDelayedWork(lazy_now);
+    base::TimeTicks next_wake_up_time;
+    int next_wake_up_sequence_num;
+    bool needs_wake_up = queue->WakeUpForDelayedWork(
+        lazy_now, &next_wake_up_time, &next_wake_up_sequence_num);
 
-    if (next_wakeup) {
+    if (needs_wake_up) {
       // O(log n)
-      delayed_wakeup_queue_.ReplaceMin({next_wakeup.value(), queue});
-      queue->set_scheduled_time_domain_wakeup(next_wakeup.value());
+      delayed_wakeup_queue_.ReplaceMin(
+          {next_wake_up_time, next_wake_up_sequence_num, queue});
+      queue->set_scheduled_time_domain_wakeup(next_wake_up_time);
     } else {
       // O(log n)
       delayed_wakeup_queue_.pop();