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

chrome/browser/chromeos/tether/tether_service.h

Index: chrome/browser/chromeos/tether/tether_service.h
diff --git a/chrome/browser/chromeos/tether/tether_service.h b/chrome/browser/chromeos/tether/tether_service.h
new file mode 100644
index 0000000000000000000000000000000000000000..bfd2a72e495dce769b3e49413e84814bb83c60de
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+++ b/chrome/browser/chromeos/tether/tether_service.h
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+// 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_TETHER_TETHER_SERVICE_H_
+#define CHROME_BROWSER_CHROMEOS_TETHER_TETHER_SERVICE_H_
+
+#include <memory>
+
+#include "base/macros.h"
+#include "components/keyed_service/core/keyed_service.h"
+#include "components/prefs/pref_change_registrar.h"
+
+namespace user_prefs {
+class PrefRegistrySyncable;
+}
+
+class Profile;
+
+class TetherService : public KeyedService {
+ public:
+  explicit TetherService(Profile* profile);
+  ~TetherService() override;
+
+  // Gets TetherService instance.
+  static TetherService* Get(Profile* profile);
+
+  static void RegisterProfilePrefs(user_prefs::PrefRegistrySyncable* registry);
+
+  // Start the Tether module. Should only be called once a user is logged in.
+  void StartTether();
+
+  // Whether Tether is allowed to be used. If the controlling preference
+  // is set (from policy), this returns the preference value. Otherwise, it is
+  // permitted if the flag is enabled. Virtual to allow override for testing.
+  virtual bool IsAllowed() const;
+
+ protected:
+  // KeyedService
+  void Shutdown() override;
+
+ private:
+  // Callback when the controlling pref changes.
+  void OnPrefsChanged();
+
+  Profile* profile_;
+  PrefChangeRegistrar registrar_;
+
+  // Whether the service has been shut down.
+  bool shut_down_;
+
+  DISALLOW_COPY_AND_ASSIGN(TetherService);
+};
+
+#endif  // CHROME_BROWSER_CHROMEOS_TETHER_TETHER_SERVICE_H_