[scheduler] Remove WorkerScheduler from public API.

third_party/WebKit/public/platform/scheduler/child/worker_scheduler.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 THIRD_PARTY_WEBKIT_PUBLIC_PLATFORM_SCHEDULER_CHILD_WORKER_SCHEDULER_H_
-#define THIRD_PARTY_WEBKIT_PUBLIC_PLATFORM_SCHEDULER_CHILD_WORKER_SCHEDULER_H_
-
-#include <memory>
-
-#include "base/macros.h"
-#include "base/message_loop/message_loop.h"
-#include "public/platform/scheduler/child/child_scheduler.h"
-#include "public/platform/scheduler/child/single_thread_idle_task_runner.h"
-#include "public/platform/WebCommon.h"
-
-namespace blink {
-namespace scheduler {
-class SchedulerTqmDelegate;
-
-class BLINK_PLATFORM_EXPORT WorkerScheduler : public ChildScheduler {
- public:
-  ~WorkerScheduler() override;
-  static std::unique_ptr<WorkerScheduler> Create(
-      scoped_refptr<SchedulerTqmDelegate> main_task_runner);
-
-  // Must be called before the scheduler can be used. Does any post construction
-  // initialization needed such as initializing idle period detection.
-  virtual void Init() = 0;
-
- protected:
-  WorkerScheduler();
-  DISALLOW_COPY_AND_ASSIGN(WorkerScheduler);
-};
-
-}  // namespace scheduler
-}  // namespace blink
-
-#endif  // THIRD_PARTY_WEBKIT_PUBLIC_PLATFORM_SCHEDULER_CHILD_WORKER_SCHEDULER_H_