Replace deprecated base::NonThreadSafe in chrome/browser/printing in favor of SequenceChecker.

chrome/browser/printing/background_printing_manager.cc

 // 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.
 
 #include "chrome/browser/printing/background_printing_manager.h"
 
 #include "base/location.h"
 #include "base/memory/ptr_util.h"
 #include "base/single_thread_task_runner.h"
 #include "base/stl_util.h"
@@ skipping 38 matching lines @@
 }
 void BackgroundPrintingManager::Observer::WebContentsDestroyed() {
   manager_->DeletePreviewContents(web_contents());
 }
 
 BackgroundPrintingManager::BackgroundPrintingManager() {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 }
 
 BackgroundPrintingManager::~BackgroundPrintingManager() {
-  DCHECK(CalledOnValidThread());
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
   // The might be some WebContentses still in |printing_contents_map_| at this
   // point (e.g. when the last remaining tab closes and there is still a print
   // preview WebContents trying to print). In such a case it will fail to print,
   // but we should at least clean up the observers.
   // TODO(thestig): Handle this case better.
 }
 
 void BackgroundPrintingManager::OwnPrintPreviewDialog(
     WebContents* preview_dialog) {
-  DCHECK(CalledOnValidThread());
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
   DCHECK(PrintPreviewDialogController::IsPrintPreviewDialog(preview_dialog));
   CHECK(!HasPrintPreviewDialog(preview_dialog));
 
   printing_contents_map_[preview_dialog] =
       base::MakeUnique<Observer>(this, preview_dialog);
 
   // Watch for print jobs finishing. Everything else is watched for by the
   // Observer. TODO(avi, cait): finish the job of removing this last
   // notification.
   registrar_.Add(this, chrome::NOTIFICATION_PRINT_JOB_RELEASED,
@@ skipping 61 matching lines @@
 
   return result;
 }
 
 bool BackgroundPrintingManager::HasPrintPreviewDialog(
     WebContents* preview_dialog) {
   return base::ContainsKey(printing_contents_map_, preview_dialog);
 }
 
 }  // namespace printing