Introduce a SchedulerHelper in content/child/scheduler

content/renderer/scheduler/renderer_scheduler_impl.cc

Index: content/renderer/scheduler/renderer_scheduler_impl.cc
diff --git a/content/renderer/scheduler/renderer_scheduler_impl.cc b/content/renderer/scheduler/renderer_scheduler_impl.cc
index 53281b81a807a7389d7e3917b86ef822d5c3bcc4..94067bda9d7e6a13b4baab9991f3f84b225812c5 100644
--- a/content/renderer/scheduler/renderer_scheduler_impl.cc
+++ b/content/renderer/scheduler/renderer_scheduler_impl.cc
@@ -9,76 +9,41 @@
 #include "base/trace_event/trace_event.h"
 #include "base/trace_event/trace_event_argument.h"
 #include "cc/output/begin_frame_args.h"
-#include "content/renderer/scheduler/nestable_single_thread_task_runner.h"
-#include "content/renderer/scheduler/renderer_task_queue_selector.h"
+#include "content/child/scheduler/nestable_single_thread_task_runner.h"
+#include "content/child/scheduler/prioritizing_task_queue_selector.h"
 #include "ui/gfx/frame_time.h"
 
 namespace content {
 
 RendererSchedulerImpl::RendererSchedulerImpl(
     scoped_refptr<NestableSingleThreadTaskRunner> main_task_runner)
-    : renderer_task_queue_selector_(new RendererTaskQueueSelector()),
-      task_queue_manager_(
-          new TaskQueueManager(TASK_QUEUE_COUNT,
-                               main_task_runner,
-                               renderer_task_queue_selector_.get())),
-      control_task_runner_(
-          task_queue_manager_->TaskRunnerForQueue(CONTROL_TASK_QUEUE)),
-      control_task_after_wakeup_runner_(task_queue_manager_->TaskRunnerForQueue(
-          CONTROL_TASK_AFTER_WAKEUP_QUEUE)),
-      default_task_runner_(
-          task_queue_manager_->TaskRunnerForQueue(DEFAULT_TASK_QUEUE)),
+    : helper_(main_task_runner,
+              this,
+              "renderer.scheduler",
+              TRACE_DISABLED_BY_DEFAULT("renderer.scheduler"),
+              TASK_QUEUE_COUNT),
+      control_task_runner_(helper_.ControlTaskRunner()),
       compositor_task_runner_(
-          task_queue_manager_->TaskRunnerForQueue(COMPOSITOR_TASK_QUEUE)),
+          helper_.SchedulerTaskQueueManager()->TaskRunnerForQueue(
+              COMPOSITOR_TASK_QUEUE)),
       loading_task_runner_(
-          task_queue_manager_->TaskRunnerForQueue(LOADING_TASK_QUEUE)),
+          helper_.SchedulerTaskQueueManager()->TaskRunnerForQueue(
+              LOADING_TASK_QUEUE)),
       delayed_update_policy_runner_(
           base::Bind(&RendererSchedulerImpl::UpdatePolicy,
                      base::Unretained(this)),
-          control_task_runner_),
+          helper_.ControlTaskRunner()),
       current_policy_(Policy::NORMAL),
-      idle_period_state_(IdlePeriodState::NOT_IN_IDLE_PERIOD),
       last_input_type_(blink::WebInputEvent::Undefined),
       input_stream_state_(InputStreamState::INACTIVE),
       policy_may_need_update_(&incoming_signals_lock_),
       weak_factory_(this) {
-  weak_renderer_scheduler_ptr_ = weak_factory_.GetWeakPtr();
   update_policy_closure_ = base::Bind(&RendererSchedulerImpl::UpdatePolicy,
-                                      weak_renderer_scheduler_ptr_);
-  end_idle_period_closure_.Reset(base::Bind(
-      &RendererSchedulerImpl::EndIdlePeriod, weak_renderer_scheduler_ptr_));
-  initiate_next_long_idle_period_closure_.Reset(base::Bind(
-      &RendererSchedulerImpl::InitiateLongIdlePeriod,
-      weak_renderer_scheduler_ptr_));
-  initiate_next_long_idle_period_after_wakeup_closure_.Reset(base::Bind(
-      &RendererSchedulerImpl::InitiateLongIdlePeriodAfterWakeup,
-      weak_renderer_scheduler_ptr_));
-
-  idle_task_runner_ = make_scoped_refptr(new SingleThreadIdleTaskRunner(
-      task_queue_manager_->TaskRunnerForQueue(IDLE_TASK_QUEUE),
-      control_task_after_wakeup_runner_,
-      base::Bind(&RendererSchedulerImpl::CurrentIdleTaskDeadlineCallback,
-                 weak_renderer_scheduler_ptr_)));
-
-  renderer_task_queue_selector_->SetQueuePriority(
-      CONTROL_TASK_QUEUE, RendererTaskQueueSelector::CONTROL_PRIORITY);
-
-  renderer_task_queue_selector_->SetQueuePriority(
-      CONTROL_TASK_AFTER_WAKEUP_QUEUE,
-      RendererTaskQueueSelector::CONTROL_PRIORITY);
-  task_queue_manager_->SetPumpPolicy(
-      CONTROL_TASK_AFTER_WAKEUP_QUEUE,
-      TaskQueueManager::PumpPolicy::AFTER_WAKEUP);
-
-  renderer_task_queue_selector_->DisableQueue(IDLE_TASK_QUEUE);
-  task_queue_manager_->SetPumpPolicy(IDLE_TASK_QUEUE,
-                                     TaskQueueManager::PumpPolicy::MANUAL);
-
-  // TODO(skyostil): Increase this to 4 (crbug.com/444764).
-  task_queue_manager_->SetWorkBatchSize(1);
-
-  for (size_t i = 0; i < TASK_QUEUE_COUNT; i++) {
-    task_queue_manager_->SetQueueName(
+                                      weak_factory_.GetWeakPtr());
+  for (size_t i = SchedulerHelper::TASK_QUEUE_COUNT;
+       i < TASK_QUEUE_COUNT;
+       i++) {
+    helper_.SchedulerTaskQueueManager()->SetQueueName(
         i, TaskQueueIdToString(static_cast<QueueId>(i)));
   }
   TRACE_EVENT_OBJECT_CREATED_WITH_ID(
@@ -93,42 +58,53 @@ RendererSchedulerImpl::~RendererSchedulerImpl() {
 }
 
 void RendererSchedulerImpl::Shutdown() {
-  DCHECK(main_thread_checker_.CalledOnValidThread());
-  task_queue_manager_.reset();
+  helper_.Shutdown();
 }
 
 scoped_refptr<base::SingleThreadTaskRunner>
 RendererSchedulerImpl::DefaultTaskRunner() {
-  DCHECK(main_thread_checker_.CalledOnValidThread());
-  return default_task_runner_;
+  return helper_.DefaultTaskRunner();
 }
 
 scoped_refptr<base::SingleThreadTaskRunner>
 RendererSchedulerImpl::CompositorTaskRunner() {
-  DCHECK(main_thread_checker_.CalledOnValidThread());
+  helper_.CheckOnValidThread();
   return compositor_task_runner_;
 }
 
 scoped_refptr<SingleThreadIdleTaskRunner>
 RendererSchedulerImpl::IdleTaskRunner() {
-  DCHECK(main_thread_checker_.CalledOnValidThread());
-  return idle_task_runner_;
+  return helper_.IdleTaskRunner();
 }
 
 scoped_refptr<base::SingleThreadTaskRunner>
 RendererSchedulerImpl::LoadingTaskRunner() {
-  DCHECK(main_thread_checker_.CalledOnValidThread());
+  helper_.CheckOnValidThread();
   return loading_task_runner_;
 }
 
+bool RendererSchedulerImpl::CanExceedIdleDeadlineIfRequired() const {
+  return helper_.CanExceedIdleDeadlineIfRequired();
+}
+
+void RendererSchedulerImpl::AddTaskObserver(
+    base::MessageLoop::TaskObserver* task_observer) {
+  helper_.AddTaskObserver(task_observer);
+}
+
+void RendererSchedulerImpl::RemoveTaskObserver(
+    base::MessageLoop::TaskObserver* task_observer) {
+  helper_.RemoveTaskObserver(task_observer);
+}
+
 void RendererSchedulerImpl::WillBeginFrame(const cc::BeginFrameArgs& args) {
   TRACE_EVENT1(TRACE_DISABLED_BY_DEFAULT("renderer.scheduler"),
                "RendererSchedulerImpl::WillBeginFrame", "args", args.AsValue());
-  DCHECK(main_thread_checker_.CalledOnValidThread());
-  if (!task_queue_manager_)
+  helper_.CheckOnValidThread();
+  if (helper_.IsShutdown())
     return;
 
-  EndIdlePeriod();
+  helper_.EndIdlePeriod();
   estimated_next_frame_begin_ = args.frame_time + args.interval;
   // TODO(skyostil): Wire up real notification of input events processing
   // instead of this approximation.
@@ -138,33 +114,34 @@ void RendererSchedulerImpl::WillBeginFrame(const cc::BeginFrameArgs& args) {
 void RendererSchedulerImpl::DidCommitFrameToCompositor() {
   TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("renderer.scheduler"),
                "RendererSchedulerImpl::DidCommitFrameToCompositor");
-  DCHECK(main_thread_checker_.CalledOnValidThread());
-  if (!task_queue_manager_)
+  helper_.CheckOnValidThread();
+  if (helper_.IsShutdown())
     return;
 
-  base::TimeTicks now(Now());
+  base::TimeTicks now(helper_.Now());
   if (now < estimated_next_frame_begin_) {
     // TODO(rmcilroy): Consider reducing the idle period based on the runtime of
     // the next pending delayed tasks (as currently done in for long idle times)
-    StartIdlePeriod(IdlePeriodState::IN_SHORT_IDLE_PERIOD);
-    control_task_runner_->PostDelayedTask(FROM_HERE,
-                                          end_idle_period_closure_.callback(),
-                                          estimated_next_frame_begin_ - now);
+    helper_.StartIdlePeriod(
+        SchedulerHelper::IdlePeriodState::IN_SHORT_IDLE_PERIOD,
+        now,
+        estimated_next_frame_begin_,
+        true);
   }
 }
 
 void RendererSchedulerImpl::BeginFrameNotExpectedSoon() {
   TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("renderer.scheduler"),
                "RendererSchedulerImpl::BeginFrameNotExpectedSoon");
-  DCHECK(main_thread_checker_.CalledOnValidThread());
-  if (!task_queue_manager_)
+  helper_.CheckOnValidThread();
+  if (helper_.IsShutdown())
     return;
 
   // TODO(skyostil): Wire up real notification of input events processing
   // instead of this approximation.
   DidProcessInputEvent(base::TimeTicks());
 
-  InitiateLongIdlePeriod();
+  helper_.InitiateLongIdlePeriod();
 }
 
 void RendererSchedulerImpl::DidReceiveInputEventOnCompositorThread(
@@ -206,7 +183,7 @@ void RendererSchedulerImpl::UpdateForInputEvent(
     input_stream_state_ = new_input_stream_state;
     EnsureUrgentPolicyUpdatePostedOnMainThread(FROM_HERE);
   }
-  last_input_receipt_time_on_compositor_ = Now();
+  last_input_receipt_time_on_compositor_ = helper_.Now();
   // Clear the last known input processing time so that we know an input event
   // is still queued up. This timestamp will be updated the next time the
   // compositor commits or becomes quiescent. Note that this function is always
@@ -218,7 +195,7 @@ void RendererSchedulerImpl::UpdateForInputEvent(
 
 void RendererSchedulerImpl::DidProcessInputEvent(
     base::TimeTicks begin_frame_time) {
-  DCHECK(main_thread_checker_.CalledOnValidThread());
+  helper_.CheckOnValidThread();
   base::AutoLock lock(incoming_signals_lock_);
   if (input_stream_state_ == InputStreamState::INACTIVE)
     return;
@@ -226,13 +203,13 @@ void RendererSchedulerImpl::DidProcessInputEvent(
   if (!begin_frame_time.is_null() &&
       begin_frame_time < last_input_receipt_time_on_compositor_)
     return;
-  last_input_process_time_on_main_ = Now();
+  last_input_process_time_on_main_ = helper_.Now();
   UpdatePolicyLocked();
 }
 
 bool RendererSchedulerImpl::IsHighPriorityWorkAnticipated() {
-  DCHECK(main_thread_checker_.CalledOnValidThread());
-  if (!task_queue_manager_)
+  helper_.CheckOnValidThread();
+  if (helper_.IsShutdown())
     return false;
 
   MaybeUpdatePolicy();
@@ -243,8 +220,8 @@ bool RendererSchedulerImpl::IsHighPriorityWorkAnticipated() {
 }
 
 bool RendererSchedulerImpl::ShouldYieldForHighPriorityWork() {
-  DCHECK(main_thread_checker_.CalledOnValidThread());
-  if (!task_queue_manager_)
+  helper_.CheckOnValidThread();
+  if (helper_.IsShutdown())
     return false;
 
   MaybeUpdatePolicy();
@@ -258,7 +235,8 @@ bool RendererSchedulerImpl::ShouldYieldForHighPriorityWork() {
       return false;
 
     case Policy::COMPOSITOR_PRIORITY:
-      return !task_queue_manager_->IsQueueEmpty(COMPOSITOR_TASK_QUEUE);
+      return !helper_.SchedulerTaskQueueManager()->IsQueueEmpty(
+          COMPOSITOR_TASK_QUEUE);
 
     case Policy::TOUCHSTART_PRIORITY:
       return true;
@@ -269,19 +247,20 @@ bool RendererSchedulerImpl::ShouldYieldForHighPriorityWork() {
   }
 }
 
-void RendererSchedulerImpl::CurrentIdleTaskDeadlineCallback(
-    base::TimeTicks* deadline_out) const {
-  DCHECK(main_thread_checker_.CalledOnValidThread());
-  *deadline_out = estimated_next_frame_begin_;
+base::TimeTicks
+RendererSchedulerImpl::CurrentIdleTaskDeadlineForTesting() const {
+  base::TimeTicks deadline;
+  helper_.CurrentIdleTaskDeadlineCallback(&deadline);
+  return deadline;
 }
 
 RendererSchedulerImpl::Policy RendererSchedulerImpl::SchedulerPolicy() const {
-  DCHECK(main_thread_checker_.CalledOnValidThread());
+  helper_.CheckOnValidThread();
   return current_policy_;
 }
 
 void RendererSchedulerImpl::MaybeUpdatePolicy() {
-  DCHECK(main_thread_checker_.CalledOnValidThread());
+  helper_.CheckOnValidThread();
   if (policy_may_need_update_.IsSet()) {
     UpdatePolicy();
   }
@@ -304,12 +283,12 @@ void RendererSchedulerImpl::UpdatePolicy() {
 }
 
 void RendererSchedulerImpl::UpdatePolicyLocked() {
-  DCHECK(main_thread_checker_.CalledOnValidThread());
+  helper_.CheckOnValidThread();
   incoming_signals_lock_.AssertAcquired();
-  if (!task_queue_manager_)
+  if (helper_.IsShutdown())
     return;
 
-  base::TimeTicks now = Now();
+  base::TimeTicks now = helper_.Now();
   policy_may_need_update_.SetWhileLocked(false);
 
   base::TimeDelta new_policy_duration;
@@ -325,30 +304,35 @@ void RendererSchedulerImpl::UpdatePolicyLocked() {
   if (new_policy == current_policy_)
     return;
 
+  PrioritizingTaskQueueSelector* task_queue_selector =
+      helper_.SchedulerTaskQueueSelector();
+
   switch (new_policy) {
     case Policy::COMPOSITOR_PRIORITY:
-      renderer_task_queue_selector_->SetQueuePriority(
-          COMPOSITOR_TASK_QUEUE, RendererTaskQueueSelector::HIGH_PRIORITY);
+      task_queue_selector->SetQueuePriority(
+          COMPOSITOR_TASK_QUEUE, PrioritizingTaskQueueSelector::HIGH_PRIORITY);
       // TODO(scheduler-dev): Add a task priority between HIGH and BEST_EFFORT
       // that still has some guarantee of running.
-      renderer_task_queue_selector_->SetQueuePriority(
-          LOADING_TASK_QUEUE, RendererTaskQueueSelector::BEST_EFFORT_PRIORITY);
+      task_queue_selector->SetQueuePriority(
+          LOADING_TASK_QUEUE,
+          PrioritizingTaskQueueSelector::BEST_EFFORT_PRIORITY);
       break;
     case Policy::TOUCHSTART_PRIORITY:
-      renderer_task_queue_selector_->SetQueuePriority(
-          COMPOSITOR_TASK_QUEUE, RendererTaskQueueSelector::HIGH_PRIORITY);
-      renderer_task_queue_selector_->DisableQueue(LOADING_TASK_QUEUE);
+      task_queue_selector->SetQueuePriority(
+          COMPOSITOR_TASK_QUEUE, PrioritizingTaskQueueSelector::HIGH_PRIORITY);
+      task_queue_selector->DisableQueue(LOADING_TASK_QUEUE);
       break;
     case Policy::NORMAL:
-      renderer_task_queue_selector_->SetQueuePriority(
-          COMPOSITOR_TASK_QUEUE, RendererTaskQueueSelector::NORMAL_PRIORITY);
-      renderer_task_queue_selector_->SetQueuePriority(
-          LOADING_TASK_QUEUE, RendererTaskQueueSelector::NORMAL_PRIORITY);
+      task_queue_selector->SetQueuePriority(
+          COMPOSITOR_TASK_QUEUE,
+          PrioritizingTaskQueueSelector::NORMAL_PRIORITY);
+      task_queue_selector->SetQueuePriority(
+          LOADING_TASK_QUEUE, PrioritizingTaskQueueSelector::NORMAL_PRIORITY);
       break;
   }
-  DCHECK(renderer_task_queue_selector_->IsQueueEnabled(COMPOSITOR_TASK_QUEUE));
+  DCHECK(task_queue_selector->IsQueueEnabled(COMPOSITOR_TASK_QUEUE));
   if (new_policy != Policy::TOUCHSTART_PRIORITY)
-    DCHECK(renderer_task_queue_selector_->IsQueueEnabled(LOADING_TASK_QUEUE));
+    DCHECK(task_queue_selector->IsQueueEnabled(LOADING_TASK_QUEUE));
 
   current_policy_ = new_policy;
 
@@ -362,7 +346,7 @@ void RendererSchedulerImpl::UpdatePolicyLocked() {
 RendererSchedulerImpl::Policy RendererSchedulerImpl::ComputeNewPolicy(
     base::TimeTicks now,
     base::TimeDelta* new_policy_duration) {
-  DCHECK(main_thread_checker_.CalledOnValidThread());
+  helper_.CheckOnValidThread();
   incoming_signals_lock_.AssertAcquired();
 
   Policy new_policy = Policy::NORMAL;
@@ -391,7 +375,7 @@ RendererSchedulerImpl::Policy RendererSchedulerImpl::ComputeNewPolicy(
 
 base::TimeDelta RendererSchedulerImpl::TimeLeftInInputEscalatedPolicy(
     base::TimeTicks now) const {
-  DCHECK(main_thread_checker_.CalledOnValidThread());
+  helper_.CheckOnValidThread();
   // TODO(rmcilroy): Change this to DCHECK_EQ when crbug.com/463869 is fixed.
   DCHECK(input_stream_state_ != InputStreamState::INACTIVE);
   incoming_signals_lock_.AssertAcquired();
@@ -400,7 +384,8 @@ base::TimeDelta RendererSchedulerImpl::TimeLeftInInputEscalatedPolicy(
       base::TimeDelta::FromMilliseconds(kPriorityEscalationAfterInputMillis);
   base::TimeDelta time_left_in_policy;
   if (last_input_process_time_on_main_.is_null() &&
-      !task_queue_manager_->IsQueueEmpty(COMPOSITOR_TASK_QUEUE)) {
+      !helper_.SchedulerTaskQueueManager()->IsQueueEmpty(
+          COMPOSITOR_TASK_QUEUE)) {
     // If the input event is still pending, go into input prioritized policy
     // and check again later.
     time_left_in_policy = escalated_priority_duration;
@@ -415,175 +400,28 @@ base::TimeDelta RendererSchedulerImpl::TimeLeftInInputEscalatedPolicy(
   return time_left_in_policy;
 }
 
-RendererSchedulerImpl::IdlePeriodState
-RendererSchedulerImpl::ComputeNewLongIdlePeriodState(
-    const base::TimeTicks now,
+bool RendererSchedulerImpl::CanEnterLongIdlePeriod(
+    base::TimeTicks now,
     base::TimeDelta* next_long_idle_period_delay_out) {
-  DCHECK(main_thread_checker_.CalledOnValidThread());
+  helper_.CheckOnValidThread();
 
   MaybeUpdatePolicy();
   if (SchedulerPolicy() == Policy::TOUCHSTART_PRIORITY) {
     // Don't start a long idle task in touch start priority, try again when
     // the policy is scheduled to end.
     *next_long_idle_period_delay_out = current_policy_expiration_time_ - now;
-    return IdlePeriodState::NOT_IN_IDLE_PERIOD;
-  }
-
-  base::TimeTicks next_pending_delayed_task =
-      task_queue_manager_->NextPendingDelayedTaskRunTime();
-  base::TimeDelta max_long_idle_period_duration =
-      base::TimeDelta::FromMilliseconds(kMaximumIdlePeriodMillis);
-  base::TimeDelta long_idle_period_duration;
-  if (next_pending_delayed_task.is_null()) {
-    long_idle_period_duration = max_long_idle_period_duration;
-  } else {
-    // Limit the idle period duration to be before the next pending task.
-    long_idle_period_duration = std::min(next_pending_delayed_task - now,
-                                         max_long_idle_period_duration);
-  }
-
-  if (long_idle_period_duration > base::TimeDelta()) {
-    *next_long_idle_period_delay_out = long_idle_period_duration;
-    return long_idle_period_duration == max_long_idle_period_duration
-               ? IdlePeriodState::IN_LONG_IDLE_PERIOD_WITH_MAX_DEADLINE
-               : IdlePeriodState::IN_LONG_IDLE_PERIOD;
-  } else {
-    // If we can't start the idle period yet then try again after wakeup.
-    *next_long_idle_period_delay_out = base::TimeDelta::FromMilliseconds(
-        kRetryInitiateLongIdlePeriodDelayMillis);
-    return IdlePeriodState::NOT_IN_IDLE_PERIOD;
-  }
-}
-
-void RendererSchedulerImpl::InitiateLongIdlePeriod() {
-  TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("renderer.scheduler"),
-               "InitiateLongIdlePeriod");
-  DCHECK(main_thread_checker_.CalledOnValidThread());
-
-  // End any previous idle period.
-  EndIdlePeriod();
-
-  base::TimeTicks now(Now());
-  base::TimeDelta next_long_idle_period_delay;
-  IdlePeriodState new_idle_period_state =
-      ComputeNewLongIdlePeriodState(now, &next_long_idle_period_delay);
-  if (IsInIdlePeriod(new_idle_period_state)) {
-    estimated_next_frame_begin_ = now + next_long_idle_period_delay;
-    StartIdlePeriod(new_idle_period_state);
-  }
-
-  if (task_queue_manager_->IsQueueEmpty(IDLE_TASK_QUEUE)) {
-    // If there are no current idle tasks then post the call to initiate the
-    // next idle for execution after wakeup (at which point after-wakeup idle
-    // tasks might be eligible to run or more idle tasks posted).
-    control_task_after_wakeup_runner_->PostDelayedTask(
-        FROM_HERE,
-        initiate_next_long_idle_period_after_wakeup_closure_.callback(),
-        next_long_idle_period_delay);
-  } else {
-    // Otherwise post on the normal control task queue.
-    control_task_runner_->PostDelayedTask(
-        FROM_HERE,
-        initiate_next_long_idle_period_closure_.callback(),
-        next_long_idle_period_delay);
-  }
-}
-
-void RendererSchedulerImpl::InitiateLongIdlePeriodAfterWakeup() {
-  TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("renderer.scheduler"),
-               "InitiateLongIdlePeriodAfterWakeup");
-  DCHECK(main_thread_checker_.CalledOnValidThread());
-
-  if (IsInIdlePeriod(idle_period_state_)) {
-    // Since we were asleep until now, end the async idle period trace event at
-    // the time when it would have ended were we awake.
-    TRACE_EVENT_ASYNC_END_WITH_TIMESTAMP0(
-        "renderer.scheduler", "RendererSchedulerIdlePeriod", this,
-        std::min(estimated_next_frame_begin_, Now()).ToInternalValue());
-    idle_period_state_ = IdlePeriodState::ENDING_LONG_IDLE_PERIOD;
-    EndIdlePeriod();
-  }
-
-  // Post a task to initiate the next long idle period rather than calling it
-  // directly to allow all pending PostIdleTaskAfterWakeup tasks to get enqueued
-  // on the idle task queue before the next idle period starts so they are
-  // eligible to be run during the new idle period.
-  control_task_runner_->PostTask(
-      FROM_HERE,
-      initiate_next_long_idle_period_closure_.callback());
-}
-
-void RendererSchedulerImpl::StartIdlePeriod(IdlePeriodState new_state) {
-  TRACE_EVENT_ASYNC_BEGIN0("renderer.scheduler",
-                           "RendererSchedulerIdlePeriod", this);
-  DCHECK(main_thread_checker_.CalledOnValidThread());
-  DCHECK(IsInIdlePeriod(new_state));
-
-  renderer_task_queue_selector_->EnableQueue(
-      IDLE_TASK_QUEUE, RendererTaskQueueSelector::BEST_EFFORT_PRIORITY);
-  task_queue_manager_->PumpQueue(IDLE_TASK_QUEUE);
-  idle_period_state_ = new_state;
-}
-
-void RendererSchedulerImpl::EndIdlePeriod() {
-  DCHECK(main_thread_checker_.CalledOnValidThread());
-
-  end_idle_period_closure_.Cancel();
-  initiate_next_long_idle_period_closure_.Cancel();
-  initiate_next_long_idle_period_after_wakeup_closure_.Cancel();
-
-  // If we weren't already within an idle period then early-out.
-  if (!IsInIdlePeriod(idle_period_state_))
-    return;
-
-  // If we are in the ENDING_LONG_IDLE_PERIOD state we have already logged the
-  // trace event.
-  if (idle_period_state_ != IdlePeriodState::ENDING_LONG_IDLE_PERIOD) {
-    bool is_tracing;
-    TRACE_EVENT_CATEGORY_GROUP_ENABLED("renderer.scheduler", &is_tracing);
-    if (is_tracing && !estimated_next_frame_begin_.is_null() &&
-        base::TimeTicks::Now() > estimated_next_frame_begin_) {
-      TRACE_EVENT_ASYNC_STEP_INTO_WITH_TIMESTAMP0(
-          "renderer.scheduler",
-          "RendererSchedulerIdlePeriod",
-          this,
-          "DeadlineOverrun",
-          estimated_next_frame_begin_.ToInternalValue());
-    }
-    TRACE_EVENT_ASYNC_END0("renderer.scheduler",
-                           "RendererSchedulerIdlePeriod", this);
+    return false;
   }
-
-  renderer_task_queue_selector_->DisableQueue(IDLE_TASK_QUEUE);
-  idle_period_state_ = IdlePeriodState::NOT_IN_IDLE_PERIOD;
-}
-
-// static
-bool RendererSchedulerImpl::IsInIdlePeriod(IdlePeriodState state) {
-  return state != IdlePeriodState::NOT_IN_IDLE_PERIOD;
-}
-
-bool RendererSchedulerImpl::CanExceedIdleDeadlineIfRequired() const {
-  TRACE_EVENT_BEGIN0("renderer.scheduler", "CanExceedIdleDeadlineIfRequired");
-  DCHECK(main_thread_checker_.CalledOnValidThread());
-  return idle_period_state_ ==
-         IdlePeriodState::IN_LONG_IDLE_PERIOD_WITH_MAX_DEADLINE;
+  return true;
 }
 
 void RendererSchedulerImpl::SetTimeSourceForTesting(
     scoped_refptr<cc::TestNowSource> time_source) {
-  DCHECK(main_thread_checker_.CalledOnValidThread());
-  time_source_ = time_source;
-  task_queue_manager_->SetTimeSourceForTesting(time_source);
+  helper_.SetTimeSourceForTesting(time_source);
 }
 
 void RendererSchedulerImpl::SetWorkBatchSizeForTesting(size_t work_batch_size) {
-  DCHECK(main_thread_checker_.CalledOnValidThread());
-  task_queue_manager_->SetWorkBatchSize(work_batch_size);
-}
-
-base::TimeTicks RendererSchedulerImpl::Now() const {
-  return UNLIKELY(time_source_) ? time_source_->Now() : base::TimeTicks::Now();
+  helper_.SetWorkBatchSizeForTesting(work_batch_size);
 }
 
 RendererSchedulerImpl::PollableNeedsUpdateFlag::PollableNeedsUpdateFlag(
@@ -607,21 +445,13 @@ bool RendererSchedulerImpl::PollableNeedsUpdateFlag::IsSet() const {
 // static
 const char* RendererSchedulerImpl::TaskQueueIdToString(QueueId queue_id) {
   switch (queue_id) {
-    case DEFAULT_TASK_QUEUE:
-      return "default_tq";
     case COMPOSITOR_TASK_QUEUE:
       return "compositor_tq";
     case LOADING_TASK_QUEUE:
       return "loading_tq";
-    case IDLE_TASK_QUEUE:
-      return "idle_tq";
-    case CONTROL_TASK_QUEUE:
-      return "control_tq";
-    case CONTROL_TASK_AFTER_WAKEUP_QUEUE:
-      return "control_after_wakeup_tq";
     default:
-      NOTREACHED();
-      return nullptr;
+      return SchedulerHelper::TaskQueueIdToString(
+          static_cast<SchedulerHelper::QueueId>(queue_id));
   }
 }
 
@@ -655,38 +485,20 @@ const char* RendererSchedulerImpl::InputStreamStateToString(
   }
 }
 
-const char* RendererSchedulerImpl::IdlePeriodStateToString(
-    IdlePeriodState idle_period_state) {
-  switch (idle_period_state) {
-    case IdlePeriodState::NOT_IN_IDLE_PERIOD:
-      return "not_in_idle_period";
-    case IdlePeriodState::IN_SHORT_IDLE_PERIOD:
-      return "in_short_idle_period";
-    case IdlePeriodState::IN_LONG_IDLE_PERIOD:
-      return "in_long_idle_period";
-    case IdlePeriodState::IN_LONG_IDLE_PERIOD_WITH_MAX_DEADLINE:
-      return "in_long_idle_period_with_max_deadline";
-    case IdlePeriodState::ENDING_LONG_IDLE_PERIOD:
-      return "ending_long_idle_period";
-    default:
-      NOTREACHED();
-      return nullptr;
-  }
-}
-
 scoped_refptr<base::trace_event::ConvertableToTraceFormat>
 RendererSchedulerImpl::AsValueLocked(base::TimeTicks optional_now) const {
-  DCHECK(main_thread_checker_.CalledOnValidThread());
+  helper_.CheckOnValidThread();
   incoming_signals_lock_.AssertAcquired();
 
   if (optional_now.is_null())
-    optional_now = Now();
+    optional_now = helper_.Now();
   scoped_refptr<base::trace_event::TracedValue> state =
       new base::trace_event::TracedValue();
 
   state->SetString("current_policy", PolicyToString(current_policy_));
   state->SetString("idle_period_state",
-                   IdlePeriodStateToString(idle_period_state_));
+                   SchedulerHelper::IdlePeriodStateToString(
+                       helper_.SchedulerIdlePeriodState()));
   state->SetString("input_stream_state",
                    InputStreamStateToString(input_stream_state_));
   state->SetDouble("now", (optional_now - base::TimeTicks()).InMillisecondsF());
@@ -739,18 +551,4 @@ RendererSchedulerImpl::ComputeNewInputStreamState(
   return InputStreamState::ACTIVE;
 }
 
-void RendererSchedulerImpl::AddTaskObserver(
-    base::MessageLoop::TaskObserver* task_observer) {
-  DCHECK(main_thread_checker_.CalledOnValidThread());
-  if (task_queue_manager_)
-    task_queue_manager_->AddTaskObserver(task_observer);
-}
-
-void RendererSchedulerImpl::RemoveTaskObserver(
-    base::MessageLoop::TaskObserver* task_observer) {
-  DCHECK(main_thread_checker_.CalledOnValidThread());
-  if (task_queue_manager_)
-    task_queue_manager_->RemoveTaskObserver(task_observer);
-}
-
 }  // namespace content