Remove base::NonThreadSafe now that all users are gone!!

chrome/browser/printing/print_job_manager.h

 // Copyright (c) 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 CHROME_BROWSER_PRINTING_PRINT_JOB_MANAGER_H_
 #define CHROME_BROWSER_PRINTING_PRINT_JOB_MANAGER_H_
 
 #include <memory>
 #include <set>
 #include <vector>
 
 #include "base/logging.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/synchronization/lock.h"
-#include "base/threading/non_thread_safe.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
 
 namespace printing {
 
 class JobEventDetails;
 class PrintJob;
 class PrinterQuery;
 
 class PrintQueriesQueue : public base::RefCountedThreadSafe<PrintQueriesQueue> {
@@ skipping 65 matching lines @@
   scoped_refptr<PrintQueriesQueue> queue_;
 
   bool is_shutdown_;
 
   DISALLOW_COPY_AND_ASSIGN(PrintJobManager);
 };
 
 }  // namespace printing
 
 #endif  // CHROME_BROWSER_PRINTING_PRINT_JOB_MANAGER_H_