Convert to CupsPrintJobManagerImpl to TaskScheduler.

chrome/browser/chromeos/printing/cups_print_job_manager_impl.h

 // Copyright 2017 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 CHROME_BROWSER_CHROMEOS_PRINTING_CUPS_PRINT_JOB_MANAGER_IMPL_H_
 #define CHROME_BROWSER_CHROMEOS_PRINTING_CUPS_PRINT_JOB_MANAGER_IMPL_H_
 
 #include <map>
 #include <memory>
 #include <string>
 #include <unordered_map>
 #include <vector>
 
+#include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
+#include "base/sequenced_task_runner.h"
 #include "chrome/browser/chromeos/printing/cups_print_job.h"
 #include "chrome/browser/chromeos/printing/cups_print_job_manager.h"
 #include "chrome/browser/chromeos/printing/printers_manager.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
 #include "printing/backend/cups_connection.h"
 
 class Profile;
 
 namespace chromeos {
@@ skipping 62 matching lines @@
   std::map<std::string, std::unique_ptr<CupsPrintJob>> jobs_;
 
   // Prevents multiple queries from being scheduled simultaneously.
   bool in_query_ = false;
 
   // Records the number of consecutive times the GetJobs query has failed.
   int retry_count_ = 0;
 
   ::printing::CupsConnection cups_connection_;
   content::NotificationRegistrar registrar_;
+  scoped_refptr<base::SequencedTaskRunner> query_runner_;
   base::WeakPtrFactory<CupsPrintJobManagerImpl> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(CupsPrintJobManagerImpl);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_PRINTING_CUPS_PRINT_JOB_MANAGER_IMPL_H_