Revert of [scheduler] Change TaskQueue observer call mechanism.

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

Index: third_party/WebKit/Source/platform/scheduler/base/task_queue_impl.cc
diff --git a/third_party/WebKit/Source/platform/scheduler/base/task_queue_impl.cc b/third_party/WebKit/Source/platform/scheduler/base/task_queue_impl.cc
index 2ead6857ad27f2719dfad5844021be6b397c79fb..5e5d7b7444be62146d1158e0bfb2fc3b3ae05459 100644
--- a/third_party/WebKit/Source/platform/scheduler/base/task_queue_impl.cc
+++ b/third_party/WebKit/Source/platform/scheduler/base/task_queue_impl.cc
@@ -402,7 +402,7 @@
   return task_count;
 }
 
-bool TaskQueueImpl::HasTaskToRunImmediately() const {
+bool TaskQueueImpl::HasPendingImmediateWork() const {
   // Any work queue tasks count as immediate work.
   if (!main_thread_only().delayed_work_queue->Empty() ||
       !main_thread_only().immediate_work_queue->Empty()) {
@@ -821,11 +821,8 @@
     return;
 
   if (enable) {
-    if (HasPendingImmediateWork() && main_thread_only().observer) {
-      // Delayed work notification will be issued via time domain.
-      main_thread_only().observer->OnQueueNextWakeUpChanged(this,
-                                                            base::TimeTicks());
-    }
+    if (HasPendingImmediateWork())
+      NotifyWakeUpChangedOnMainThread(base::TimeTicks());
 
     ScheduleDelayedWorkInTimeDomain(main_thread_only().time_domain->Now());
 
@@ -902,33 +899,14 @@
   main_thread_only().time_domain->ScheduleDelayedWork(
       this, main_thread_only().delayed_incoming_queue.top().delayed_wake_up(),
       now);
-}
-
-void TaskQueueImpl::SetScheduledTimeDomainWakeUp(
-    base::Optional<base::TimeTicks> scheduled_time_domain_wake_up) {
-  main_thread_only().scheduled_time_domain_wake_up =
-      scheduled_time_domain_wake_up;
-
-  // If queue has immediate work an appropriate notification has already
-  // been issued.
-  if (!scheduled_time_domain_wake_up || !main_thread_only().observer ||
-      HasPendingImmediateWork())
-    return;
-
-  main_thread_only().observer->OnQueueNextWakeUpChanged(
-      this, scheduled_time_domain_wake_up.value());
-}
-
-bool TaskQueueImpl::HasPendingImmediateWork() {
-  // Any work queue tasks count as immediate work.
-  if (!main_thread_only().delayed_work_queue->Empty() ||
-      !main_thread_only().immediate_work_queue->Empty()) {
-    return true;
-  }
-
-  // Finally tasks on |immediate_incoming_queue| count as immediate work.
-  base::AutoLock lock(immediate_incoming_queue_lock_);
-  return !immediate_incoming_queue().empty();
+
+  NotifyWakeUpChangedOnMainThread(
+      main_thread_only().delayed_incoming_queue.top().delayed_run_time);
+}
+
+void TaskQueueImpl::NotifyWakeUpChangedOnMainThread(base::TimeTicks wake_up) {
+  if (main_thread_only().observer)
+    main_thread_only().observer->OnQueueNextWakeUpChanged(this, wake_up);
 }
 
 }  // namespace internal