[Try # 3] Scheduler refactoring to virtually eliminate redundant DoWorks

third_party/WebKit/Source/platform/scheduler/child/scheduler_helper.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/child/scheduler_helper.h"
 
 #include "base/time/default_tick_clock.h"
 #include "base/trace_event/trace_event.h"
 #include "base/trace_event/trace_event_argument.h"
 #include "platform/scheduler/base/task_queue_impl.h"
 #include "platform/scheduler/child/scheduler_tqm_delegate.h"
 
 namespace blink {
 namespace scheduler {
 
 SchedulerHelper::SchedulerHelper(
     scoped_refptr<SchedulerTqmDelegate> task_queue_manager_delegate,
     const char* tracing_category,
     const char* disabled_by_default_tracing_category,
     const char* disabled_by_default_verbose_tracing_category)
+    : SchedulerHelper(task_queue_manager_delegate,
+                      tracing_category,
+                      disabled_by_default_tracing_category,
+                      disabled_by_default_verbose_tracing_category,
+                      TaskQueue::Spec(TaskQueue::QueueType::DEFAULT)
+                          .SetShouldMonitorQuiescence(true)) {}
+
+SchedulerHelper::SchedulerHelper(
+    scoped_refptr<SchedulerTqmDelegate> task_queue_manager_delegate,
+    const char* tracing_category,
+    const char* disabled_by_default_tracing_category,
+    const char* disabled_by_default_verbose_tracing_category,
+    TaskQueue::Spec default_task_queue_spec)
     : task_queue_manager_delegate_(task_queue_manager_delegate),
       task_queue_manager_(
           new TaskQueueManager(task_queue_manager_delegate,
                                tracing_category,
                                disabled_by_default_tracing_category,
                                disabled_by_default_verbose_tracing_category)),
       control_task_runner_(
           NewTaskQueue(TaskQueue::Spec(TaskQueue::QueueType::CONTROL)
                            .SetShouldNotifyObservers(false))),
-      default_task_runner_(
-          NewTaskQueue(TaskQueue::Spec(TaskQueue::QueueType::DEFAULT)
-                           .SetShouldMonitorQuiescence(true))),
+      default_task_runner_(NewTaskQueue(default_task_queue_spec)),
       observer_(nullptr),
       tracing_category_(tracing_category),
       disabled_by_default_tracing_category_(
           disabled_by_default_tracing_category) {
   control_task_runner_->SetQueuePriority(TaskQueue::CONTROL_PRIORITY);
 
   task_queue_manager_->SetWorkBatchSize(4);
 
   DCHECK(task_queue_manager_delegate_);
   task_queue_manager_delegate_->SetDefaultTaskRunner(
       default_task_runner_.get());
 }
 
 SchedulerHelper::~SchedulerHelper() {
   Shutdown();
 }
 
 void SchedulerHelper::Shutdown() {
   CheckOnValidThread();
   if (task_queue_manager_)
     task_queue_manager_->SetObserver(nullptr);
   task_queue_manager_.reset();
   task_queue_manager_delegate_->RestoreDefaultTaskRunner();
 }
 
+void SchedulerHelper::SetRecordTaskDelayHistograms(
+    bool record_task_delay_histograms) {
+  if (!task_queue_manager_)
+    return;
+
+  task_queue_manager_->SetRecordTaskDelayHistograms(
+      record_task_delay_histograms);
+}
+
 scoped_refptr<TaskQueue> SchedulerHelper::NewTaskQueue(
     const TaskQueue::Spec& spec) {
   DCHECK(task_queue_manager_.get());
   return task_queue_manager_->NewTaskQueue(spec);
 }
 
 scoped_refptr<TaskQueue> SchedulerHelper::DefaultTaskRunner() {
   CheckOnValidThread();
   return default_task_runner_;
 }
@@ skipping 61 matching lines @@
   task_queue_manager_->SetObserver(this);
 }
 
 void SchedulerHelper::SweepCanceledDelayedTasks() {
   CheckOnValidThread();
   DCHECK(task_queue_manager_);
   task_queue_manager_->SweepCanceledDelayedTasks();
 }
 
 RealTimeDomain* SchedulerHelper::real_time_domain() const {
-  CheckOnValidThread();
-  DCHECK(task_queue_manager_);
+  if (!task_queue_manager_)
+    return nullptr;
   return task_queue_manager_->real_time_domain();
 }
 
 void SchedulerHelper::RegisterTimeDomain(TimeDomain* time_domain) {
   CheckOnValidThread();
   DCHECK(task_queue_manager_);
   task_queue_manager_->RegisterTimeDomain(time_domain);
 }
 
 void SchedulerHelper::UnregisterTimeDomain(TimeDomain* time_domain) {
@@ skipping 16 matching lines @@
 }
 
 TaskQueue* SchedulerHelper::CurrentlyExecutingTaskQueue() const {
   if (!task_queue_manager_)
     return nullptr;
   return task_queue_manager_->currently_executing_task_queue();
 }
 
 }  // namespace scheduler
 }  // namespace blink