Task Scheduler API migration: change BrowserThreadModelWorker to SequencedModelWorker

components/sync/engine/browser_thread_model_worker.h

-// Copyright 2012 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_SYNC_ENGINE_BROWSER_THREAD_MODEL_WORKER_H_
-#define COMPONENTS_SYNC_ENGINE_BROWSER_THREAD_MODEL_WORKER_H_
-
-#include "base/macros.h"
-#include "base/memory/ref_counted.h"
-#include "base/single_thread_task_runner.h"
-#include "components/sync/engine/model_safe_worker.h"
-
-namespace syncer {
-
-// A ModelSafeWorker for models that accept requests from the
-// syncapi that need to be fulfilled on a browser thread, for example
-// autofill on the DB thread.
-// TODO(sync): Try to generalize other ModelWorkers (e.g. history, etc).
-class BrowserThreadModelWorker : public ModelSafeWorker {
- public:
-  BrowserThreadModelWorker(
-      const scoped_refptr<base::SingleThreadTaskRunner>& runner,
-      ModelSafeGroup group);
-
-  // ModelSafeWorker implementation.
-  ModelSafeGroup GetModelSafeGroup() override;
-  bool IsOnModelThread() override;
-
- private:
-  ~BrowserThreadModelWorker() override;
-
-  void ScheduleWork(base::OnceClosure work) override;
-
-  scoped_refptr<base::SingleThreadTaskRunner> runner_;
-  ModelSafeGroup group_;
-
-  DISALLOW_COPY_AND_ASSIGN(BrowserThreadModelWorker);
-};
-
-}  // namespace syncer
-
-#endif  // COMPONENTS_SYNC_ENGINE_BROWSER_THREAD_MODEL_WORKER_H_