Add device policy to disallow shutdown - ash UI modifications

chrome/browser/ui/webui/chromeos/login/shutdown_policy_observer.h

-// Copyright (c) 2014 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_UI_WEBUI_CHROMEOS_LOGIN_SHUTDOWN_POLICY_OBSERVER_H_
-#define CHROME_BROWSER_UI_WEBUI_CHROMEOS_LOGIN_SHUTDOWN_POLICY_OBSERVER_H_
-
-#include "base/callback_forward.h"
-#include "base/macros.h"
-#include "base/memory/scoped_ptr.h"
-#include "base/memory/weak_ptr.h"
-#include "chrome/browser/chromeos/settings/cros_settings.h"
-
-namespace chromeos {
-
-// This class observes the device setting |DeviceRebootOnShutdown|. Changes to
-// this policy are communicated to the ShutdownPolicyObserver::Delegate by
-// calling its OnShutdownPolicyChanged method with the new state of the policy.
-class ShutdownPolicyObserver {
- public:
-  // This callback is passed to CheckIfRebootOnShutdown, which invokes it with
-  // the current state of the |DeviceRebootOnShutdown| policy once a trusted of
-  // policies is established.
-  using RebootOnShutdownCallback = base::Callback<void(bool)>;
-
-  // This delegate is called when the |DeviceRebootOnShutdown| policy changes.
-  class Delegate {
-   public:
-    virtual void OnShutdownPolicyChanged(bool reboot_on_shutdown) = 0;
-
-   protected:
-    virtual ~Delegate() {}
-  };
-
-  ShutdownPolicyObserver(CrosSettings* cros_settings, Delegate* delegate);
-  ~ShutdownPolicyObserver();
-
-  // Once a trusted set of policies is established, this function calls
-  // |callback| with the trusted state of the |DeviceRebootOnShutdown| policy.
-  void CheckIfRebootOnShutdown(const RebootOnShutdownCallback& callback);
-
-  // Resets the policy subscription and clears the delegate.
-  void Shutdown();
-
- private:
-  void CallDelegate(bool reboot_on_shutdown);
-
-  void OnShutdownPolicyChanged();
-
-  CrosSettings* cros_settings_;
-
-  Delegate* delegate_;
-
-  scoped_ptr<CrosSettings::ObserverSubscription> shutdown_policy_subscription_;
-
-  base::WeakPtrFactory<ShutdownPolicyObserver> weak_factory_;
-
-  DISALLOW_COPY_AND_ASSIGN(ShutdownPolicyObserver);
-};
-
-}  // namespace chromeos
-
-#endif  // CHROME_BROWSER_UI_WEBUI_CHROMEOS_LOGIN_SHUTDOWN_POLICY_OBSERVER_H_