[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 6333a681ebb1329cbce7225c37c9b2325e2d1d28..aee11b13190ddc670c0663d70bb90a755cbc8c13 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 @@ size_t TaskQueueImpl::GetNumberOfPendingTasks() const {
   return task_count;
 }
 
-bool TaskQueueImpl::HasPendingImmediateWork() const {
+bool TaskQueueImpl::HasTaskToRunImmediately() const {
   // Any work queue tasks count as immediate work.
   if (!main_thread_only().delayed_work_queue->Empty() ||
       !main_thread_only().immediate_work_queue->Empty()) {
@@ -821,8 +821,10 @@ void TaskQueueImpl::EnableOrDisableWithSelector(bool enable) {
     return;
 
   if (enable) {
-    if (HasPendingImmediateWork())
-      NotifyWakeUpChangedOnMainThread(base::TimeTicks());
+    if (HasPendingImmediateWork() && main_thread_only().observer) {

[Sami, 2017/05/08 17:33:37]

This could also use a comment saying why we need to ignore ready incoming
delayed work.

[altimin, 2017/05/09 11:41:42]

Done.

+      main_thread_only().observer->OnQueueNextWakeUpChanged(this,

[Sami, 2017/05/08 17:33:37]

Could you add a TODO where OnQueueNextWakeUpChanged is defined to change the
parameter to an optional TimeTicks so we can tell the observer about
cancellations too?

[altimin, 2017/05/09 11:41:42]

Done.

+                                                            base::TimeTicks());
+    }
 
     ScheduleDelayedWorkInTimeDomain(main_thread_only().time_domain->Now());
 
@@ -899,14 +901,34 @@ void TaskQueueImpl::ScheduleDelayedWorkInTimeDomain(base::TimeTicks now) {
   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 (!scheduled_time_domain_wake_up)
+    return;
+  if (!main_thread_only().observer)
+    return;
+  if (HasPendingImmediateWork())

[Sami, 2017/05/08 17:33:37]

I'm not sure why we need to ignore ready incoming delayed tasks here -- could
you add a comment?

[altimin, 2017/05/09 11:41:42]

Done.

+    return;
 
-  NotifyWakeUpChangedOnMainThread(
-      main_thread_only().delayed_incoming_queue.top().delayed_run_time);
+  main_thread_only().observer->OnQueueNextWakeUpChanged(
+      this, scheduled_time_domain_wake_up.value());
 }
 
-void TaskQueueImpl::NotifyWakeUpChangedOnMainThread(base::TimeTicks wake_up) {
-  if (main_thread_only().observer)
-    main_thread_only().observer->OnQueueNextWakeUpChanged(this, wake_up);
+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();
 }
 
 }  // namespace internal