Create TetherService, a TetherAllowed pref, and use DependencyManager for RegisterProfilePrefs call…

chrome/browser/cryptauth/chrome_cryptauth_service_factory.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_CRYPTAUTH_CHROME_CRYPTAUTH_SERVICE_FACTORY_H_
 #define CHROME_BROWSER_CRYPTAUTH_CHROME_CRYPTAUTH_SERVICE_FACTORY_H_
 
 #include "base/macros.h"
 #include "base/memory/singleton.h"
 #include "components/cryptauth/cryptauth_service.h"
 #include "components/keyed_service/content/browser_context_keyed_service_factory.h"
 
 // Factory which is used to access the CryptAuthService singleton.
 class ChromeCryptAuthServiceFactory : public BrowserContextKeyedServiceFactory {
  public:
   static cryptauth::CryptAuthService* GetForBrowserContext(
       content::BrowserContext* context);
 
   static ChromeCryptAuthServiceFactory* GetInstance();
 
  private:
   friend struct base::DefaultSingletonTraits<ChromeCryptAuthServiceFactory>;
 
   ChromeCryptAuthServiceFactory();
   ~ChromeCryptAuthServiceFactory() override;
 
   // BrowserContextKeyedServiceFactory
   KeyedService* BuildServiceInstanceFor(
       content::BrowserContext* context) const override;
+  void RegisterProfilePrefs(
+      user_prefs::PrefRegistrySyncable* registry) override;
 
   DISALLOW_COPY_AND_ASSIGN(ChromeCryptAuthServiceFactory);
 };
 
 #endif  // CHROME_BROWSER_CRYPTAUTH_CHROME_CRYPTAUTH_SERVICE_FACTORY_H_