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

chrome/browser/extensions/warning_badge_service.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_EXTENSIONS_WARNING_BADGE_SERVICE_H_
 #define CHROME_BROWSER_EXTENSIONS_WARNING_BADGE_SERVICE_H_
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
-#include "base/threading/non_thread_safe.h"
 #include "components/keyed_service/core/keyed_service.h"
 #include "extensions/browser/warning_service.h"
 #include "extensions/browser/warning_set.h"
 
 class Profile;
 
 namespace extensions {
 
 // A service that is responsible for showing an extension warning badge on the
 // wrench menu.
 class WarningBadgeService : public KeyedService,
-                            public WarningService::Observer,
-                            public base::NonThreadSafe {
+                            public WarningService::Observer {
  public:
   explicit WarningBadgeService(Profile* profile);
   ~WarningBadgeService() override;
 
   static WarningBadgeService* Get(content::BrowserContext* context);
 
   // Black lists all currently active extension warnings, so that they do not
   // trigger a warning badge again for the life-time of the browsing session.
   void SuppressCurrentWarnings();
 
@@ skipping 16 matching lines @@
 
   // Warnings that do not trigger a badge on the wrench menu.
   WarningSet suppressed_warnings_;
 
   DISALLOW_COPY_AND_ASSIGN(WarningBadgeService);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_WARNING_BADGE_SERVICE_H_