scheduler: Move the Blink scheduler into Blink

components/scheduler/base/task_queue_manager.h

Index: components/scheduler/base/task_queue_manager.h
diff --git a/components/scheduler/base/task_queue_manager.h b/components/scheduler/base/task_queue_manager.h
deleted file mode 100644
index bb938ada00286dd6c7bcbb6261d5f8bfcb2c8530..0000000000000000000000000000000000000000
--- a/components/scheduler/base/task_queue_manager.h
+++ /dev/null
@@ -1,268 +0,0 @@
-// Copyright 2014 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.
-
-#ifndef CONTENT_RENDERER_SCHEDULER_BASE_TASK_QUEUE_MANAGER_H_
-#define CONTENT_RENDERER_SCHEDULER_BASE_TASK_QUEUE_MANAGER_H_
-
-#include <map>
-
-#include "base/atomic_sequence_num.h"
-#include "base/debug/task_annotator.h"
-#include "base/macros.h"
-#include "base/memory/weak_ptr.h"
-#include "base/message_loop/message_loop.h"
-#include "base/pending_task.h"
-#include "base/synchronization/lock.h"
-#include "base/threading/thread_checker.h"
-#include "components/scheduler/base/enqueue_order.h"
-#include "components/scheduler/base/task_queue_impl.h"
-#include "components/scheduler/base/task_queue_selector.h"
-#include "components/scheduler/scheduler_export.h"
-
-namespace base {
-class TickClock;
-
-namespace trace_event {
-class ConvertableToTraceFormat;
-class TracedValue;
-}  // namespace trace_event
-}  // namespace base
-
-namespace scheduler {
-namespace internal {
-class TaskQueueImpl;
-}  // namespace internal
-
-class LazyNow;
-class RealTimeDomain;
-class TimeDomain;
-class TaskQueueManagerDelegate;
-class TaskTimeTracker;
-
-// The task queue manager provides N task queues and a selector interface for
-// choosing which task queue to service next. Each task queue consists of two
-// sub queues:
-//
-// 1. Incoming task queue. Tasks that are posted get immediately appended here.
-//    When a task is appended into an empty incoming queue, the task manager
-//    work function (DoWork) is scheduled to run on the main task runner.
-//
-// 2. Work queue. If a work queue is empty when DoWork() is entered, tasks from
-//    the incoming task queue (if any) are moved here. The work queues are
-//    registered with the selector as input to the scheduling decision.
-//
-class SCHEDULER_EXPORT TaskQueueManager
-    : public internal::TaskQueueSelector::Observer {
- public:
-  // Create a task queue manager where |delegate| identifies the thread
-  // on which where the tasks are  eventually run. Category strings must have
-  // application lifetime (statics or literals). They may not include " chars.
-  TaskQueueManager(scoped_refptr<TaskQueueManagerDelegate> delegate,
-                   const char* tracing_category,
-                   const char* disabled_by_default_tracing_category,
-                   const char* disabled_by_default_verbose_tracing_category);
-  ~TaskQueueManager() override;
-
-  // Requests that a task to process work is posted on the main task runner.
-  // These tasks are de-duplicated in two buckets: main-thread and all other
-  // threads.  This distinction is done to reduce the overehead from locks, we
-  // assume the main-thread path will be hot.
-  void MaybeScheduleImmediateWork(const tracked_objects::Location& from_here);
-
-  // Requests that a delayed task to process work is posted on the main task
-  // runner. These delayed tasks are de-duplicated. Must be called on the thread
-  // this class was created on.
-  void MaybeScheduleDelayedWork(const tracked_objects::Location& from_here,
-                                base::TimeTicks now,
-                                base::TimeDelta delay);
-
-  // Set the number of tasks executed in a single invocation of the task queue
-  // manager. Increasing the batch size can reduce the overhead of yielding
-  // back to the main message loop -- at the cost of potentially delaying other
-  // tasks posted to the main loop. The batch size is 1 by default.
-  void SetWorkBatchSize(int work_batch_size);
-
-  // When given a non-null TaskTimeTracker, the TaskQueueManager calls its
-  // ReportTaskTime method for every top level task. The task_time_tracker must
-  // outlive this object, or be removed via SetTaskTimeTracker(nullptr).
-  void SetTaskTimeTracker(TaskTimeTracker* task_time_tracker) {
-    task_time_tracker_ = task_time_tracker;
-  }
-
-  // These functions can only be called on the same thread that the task queue
-  // manager executes its tasks on.
-  void AddTaskObserver(base::MessageLoop::TaskObserver* task_observer);
-  void RemoveTaskObserver(base::MessageLoop::TaskObserver* task_observer);
-
-  // Returns true if any task from a monitored task queue was was run since the
-  // last call to GetAndClearSystemIsQuiescentBit.
-  bool GetAndClearSystemIsQuiescentBit();
-
-  // Creates a task queue with the given |spec|.  Must be called on the thread
-  // this class was created on.
-  scoped_refptr<internal::TaskQueueImpl> NewTaskQueue(
-      const TaskQueue::Spec& spec);
-
-  class SCHEDULER_EXPORT Observer {
-   public:
-    virtual ~Observer() {}
-
-    // Called when |queue| is unregistered.
-    virtual void OnUnregisterTaskQueue(
-        const scoped_refptr<TaskQueue>& queue) = 0;
-
-    // Called when the manager tried to execute a task from a disabled
-    // queue. See TaskQueue::Spec::SetShouldReportWhenExecutionBlocked.
-    virtual void OnTriedToExecuteBlockedTask(const TaskQueue& queue,
-                                             const base::PendingTask& task) = 0;
-  };
-
-  // Called once to set the Observer. This function is called on the main
-  // thread. If |observer| is null, then no callbacks will occur.
-  // Note |observer| is expected to outlive the SchedulerHelper.
-  void SetObserver(Observer* observer);
-
-  // Returns the delegate used by the TaskQueueManager.
-  const scoped_refptr<TaskQueueManagerDelegate>& delegate() const;
-
-  // Time domains must be registered for the task queues to get updated.
-  void RegisterTimeDomain(TimeDomain* time_domain);
-  void UnregisterTimeDomain(TimeDomain* time_domain);
-
-  RealTimeDomain* real_time_domain() const { return real_time_domain_.get(); }
-
-  LazyNow CreateLazyNow() const;
-
-  // Returns the currently executing TaskQueue if any. Must be called on the
-  // thread this class was created on.
-  TaskQueue* currently_executing_task_queue() const {
-    DCHECK(main_thread_checker_.CalledOnValidThread());
-    return currently_executing_task_queue_;
-  }
-
- private:
-  friend class LazyNow;
-  friend class internal::TaskQueueImpl;
-  friend class TaskQueueManagerTest;
-
-  class DeletionSentinel : public base::RefCounted<DeletionSentinel> {
-   private:
-    friend class base::RefCounted<DeletionSentinel>;
-    ~DeletionSentinel() {}
-  };
-
-  // Unregisters a TaskQueue previously created by |NewTaskQueue()|.
-  // NOTE we have to flush the queue from |newly_updatable_| which means as a
-  // side effect MoveNewlyUpdatableQueuesIntoUpdatableQueueSet is called by this
-  // function.
-  void UnregisterTaskQueue(scoped_refptr<internal::TaskQueueImpl> task_queue);
-
-  // TaskQueueSelector::Observer implementation:
-  void OnTaskQueueEnabled(internal::TaskQueueImpl* queue) override;
-  void OnTriedToSelectBlockedWorkQueue(
-      internal::WorkQueue* work_queue) override;
-
-  // Called by the task queue to register a new pending task.
-  void DidQueueTask(const internal::TaskQueueImpl::Task& pending_task);
-
-  // Use the selector to choose a pending task and run it.
-  void DoWork(base::TimeTicks run_time, bool from_main_thread);
-
-  // Delayed Tasks with run_times <= Now() are enqueued onto the work queue.
-  // Reloads any empty work queues which have automatic pumping enabled and
-  // which are eligible to be auto pumped based on the |previous_task| which was
-  // run and |should_trigger_wakeup|. Call with an empty |previous_task| if no
-  // task was just run.
-  void UpdateWorkQueues(bool should_trigger_wakeup,
-                        const internal::TaskQueueImpl::Task* previous_task,
-                        LazyNow lazy_now);
-
-  // Chooses the next work queue to service. Returns true if |out_queue|
-  // indicates the queue from which the next task should be run, false to
-  // avoid running any tasks.
-  bool SelectWorkQueueToService(internal::WorkQueue** out_work_queue);
-
-  // Runs a single nestable task from the |queue|. On exit, |out_task| will
-  // contain the task which was executed. Non-nestable task are reposted on the
-  // run loop. The queue must not be empty.
-  enum class ProcessTaskResult {
-    DEFERRED,
-    EXECUTED,
-    TASK_QUEUE_MANAGER_DELETED
-  };
-  ProcessTaskResult ProcessTaskFromWorkQueue(
-      internal::WorkQueue* work_queue,
-      internal::TaskQueueImpl::Task* out_previous_task);
-
-  bool RunsTasksOnCurrentThread() const;
-  bool PostNonNestableDelayedTask(const tracked_objects::Location& from_here,
-                                  const base::Closure& task,
-                                  base::TimeDelta delay);
-
-  internal::EnqueueOrder GetNextSequenceNumber();
-
-  // Calls MaybeAdvanceTime on all time domains and returns true if one of them
-  // was able to advance.
-  bool TryAdvanceTimeDomains();
-
-  void MaybeRecordTaskDelayHistograms(
-      const internal::TaskQueueImpl::Task& pending_task,
-      const internal::TaskQueueImpl* queue);
-
-  std::unique_ptr<base::trace_event::ConvertableToTraceFormat>
-  AsValueWithSelectorResult(bool should_run,
-                            internal::WorkQueue* selected_work_queue) const;
-
-  std::set<TimeDomain*> time_domains_;
-  std::unique_ptr<RealTimeDomain> real_time_domain_;
-
-  std::set<scoped_refptr<internal::TaskQueueImpl>> queues_;
-
-  // We have to be careful when deleting a queue because some of the code uses
-  // raw pointers and doesn't expect the rug to be pulled out from underneath.
-  std::set<scoped_refptr<internal::TaskQueueImpl>> queues_to_delete_;
-
-  internal::EnqueueOrderGenerator enqueue_order_generator_;
-  base::debug::TaskAnnotator task_annotator_;
-
-  base::ThreadChecker main_thread_checker_;
-  scoped_refptr<TaskQueueManagerDelegate> delegate_;
-  internal::TaskQueueSelector selector_;
-
-  base::Closure from_main_thread_immediate_do_work_closure_;
-  base::Closure from_other_thread_immediate_do_work_closure_;
-
-  bool task_was_run_on_quiescence_monitored_queue_;
-
-  // To reduce locking overhead we track pending calls to DoWork separately for
-  // the main thread and other threads.
-  std::set<base::TimeTicks> main_thread_pending_wakeups_;
-
-  // Protects |other_thread_pending_wakeups_|.
-  mutable base::Lock other_thread_lock_;
-  std::set<base::TimeTicks> other_thread_pending_wakeups_;
-
-  int work_batch_size_;
-  size_t task_count_;
-
-  base::ObserverList<base::MessageLoop::TaskObserver> task_observers_;
-
-  TaskTimeTracker* task_time_tracker_;  // NOT OWNED
-
-  const char* tracing_category_;
-  const char* disabled_by_default_tracing_category_;
-  const char* disabled_by_default_verbose_tracing_category_;
-
-  internal::TaskQueueImpl* currently_executing_task_queue_;  // NOT OWNED
-
-  Observer* observer_;  // NOT OWNED
-  scoped_refptr<DeletionSentinel> deletion_sentinel_;
-  base::WeakPtrFactory<TaskQueueManager> weak_factory_;
-
-  DISALLOW_COPY_AND_ASSIGN(TaskQueueManager);
-};
-
-}  // namespace scheduler
-
-#endif  // CONTENT_RENDERER_SCHEDULER_BASE_TASK_QUEUE_MANAGER_H_