[scheduler] Change TaskQueue observer call mechanism.

third_party/WebKit/Source/platform/scheduler/base/task_queue_impl.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/task_queue_impl.h"
 
 #include <utility>
 
 #include "base/format_macros.h"
 #include "base/memory/ptr_util.h"
@@ skipping 384 matching lines @@
   size_t task_count = 0;
   task_count += main_thread_only().delayed_work_queue->Size();
   task_count += main_thread_only().delayed_incoming_queue.size();
   task_count += main_thread_only().immediate_work_queue->Size();
 
   base::AutoLock lock(immediate_incoming_queue_lock_);
   task_count += immediate_incoming_queue().size();
   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()) {
     return true;
   }
 
   // Tasks on |delayed_incoming_queue| that could run now, count as
   // immediate work.
   if (!main_thread_only().delayed_incoming_queue.empty() &&
       main_thread_only().delayed_incoming_queue.top().delayed_run_time <=
@@ skipping 398 matching lines @@
   bool is_enabled = IsQueueEnabled();
   if (was_enabled != is_enabled)
     EnableOrDisableWithSelector(is_enabled);
 }
 
 void TaskQueueImpl::EnableOrDisableWithSelector(bool enable) {
   if (!main_thread_only().task_queue_manager)
     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());
 
     // Note the selector calls TaskQueueManager::OnTaskQueueEnabled which posts
     // a DoWork if needed.
     main_thread_only().task_queue_manager->selector_.EnableQueue(this);
   } else {
     if (!main_thread_only().delayed_incoming_queue.empty())
       main_thread_only().time_domain->CancelDelayedWork(this);
     main_thread_only().task_queue_manager->selector_.DisableQueue(this);
@@ skipping 56 matching lines @@
 
 void TaskQueueImpl::ScheduleDelayedWorkInTimeDomain(base::TimeTicks now) {
   if (!IsQueueEnabled())
     return;
   if (main_thread_only().delayed_incoming_queue.empty())
     return;
 
   main_thread_only().time_domain->ScheduleDelayedWork(
       this, main_thread_only().delayed_incoming_queue.top().delayed_wake_up(),
       now);
-
-  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);
+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;
+
+  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();
 }
 
 }  // namespace internal
 }  // namespace scheduler
 }  // namespace blink