Revert of Move throttling of background timers into the renderer scheduler

components/scheduler/renderer/throttling_helper.h

-// 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.
-
-#ifndef COMPONENTS_SCHEDULER_RENDERER_THROTTLING_HELPER_H_
-#define COMPONENTS_SCHEDULER_RENDERER_THROTTLING_HELPER_H_
-
-#include <set>
-
-#include "base/macros.h"
-#include "components/scheduler/base/time_domain.h"
-#include "components/scheduler/scheduler_export.h"
-#include "third_party/WebKit/public/platform/WebViewScheduler.h"
-
-namespace scheduler {
-
-class RendererSchedulerImpl;
-class VirtualTimeDomain;
-class WebFrameSchedulerImpl;
-
-class SCHEDULER_EXPORT ThrottlingHelper : public TimeDomain::Observer {
- public:
-  ThrottlingHelper(RendererSchedulerImpl* renderer_scheduler,
-                   const char* tracing_category);
-
-  ~ThrottlingHelper() override;
-
-  // TimeDomain::Observer implementation:
-  void OnTimeDomainHasImmediateWork() override;
-  void OnTimeDomainHasDelayedWork() override;
-
-  void Throttle(TaskQueue* task_queue);
-  void Unthrottle(TaskQueue* task_queue);
-
-  const VirtualTimeDomain* time_domain() const { return time_domain_.get(); }
-
-  static base::TimeDelta DelayToNextRunTimeInSeconds(base::TimeTicks now);
-
- private:
-  void PumpThrottledTasks();
-  void MaybeSchedulePumpThrottledTasksLocked();
-
-  std::set<TaskQueue*> throttled_queues_;
-  base::Closure pump_throttled_tasks_closure_;
-  base::Closure forward_immediate_work_closure_;
-  scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
-  RendererSchedulerImpl* renderer_scheduler_;  // NOT OWNED
-  base::TickClock* tick_clock_;                // NOT OWNED
-  const char* tracing_category_;               // NOT OWNED
-  scoped_ptr<VirtualTimeDomain> time_domain_;
-
-  bool pending_pump_throttled_tasks_;
-
-  base::WeakPtrFactory<ThrottlingHelper> weak_factory_;
-
-  DISALLOW_COPY_AND_ASSIGN(ThrottlingHelper);
-};
-
-}  // namespace scheduler
-
-#endif  // COMPONENTS_SCHEDULER_RENDERER_THROTTLING_HELPER_H_