chromeos: Simplify ShutdownPolicyHandler

ash/common/system/tray/system_tray_delegate.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 ASH_COMMON_SYSTEM_TRAY_SYSTEM_TRAY_DELEGATE_H_
 #define ASH_COMMON_SYSTEM_TRAY_SYSTEM_TRAY_DELEGATE_H_
 
 #include <memory>
 #include <string>
 #include <vector>
@@ skipping 58 matching lines @@
 
   UpdateSeverity severity;
   bool update_required;
   bool factory_reset_required;
 };
 
 class CastConfigDelegate;
 class NetworkingConfigDelegate;
 class VPNDelegate;
 
-using RebootOnShutdownCallback = base::Callback<void(bool)>;
-
 // SystemTrayDelegate is intended for delegating tasks in the System Tray to the
 // application (e.g. Chrome). These tasks should be limited to application
 // (browser) specific tasks. For non application specific tasks, where possible,
 // components/, chromeos/, device/, etc., code should be used directly. If more
 // than one related method is being added, consider adding an additional
 // specific delegate (e.g. VPNDelegate).
 //
 // These methods should all have trivial default implementations for platforms
 // that do not implement the method (e.g. return false or nullptr). This
 // eliminates the need to propagate default implementations across the various
@@ skipping 134 matching lines @@
 
   // Adds an observer whose |OnShutdownPolicyChanged| function is called when
   // the |DeviceRebootOnShutdown| policy changes. If this policy is set to
   // true, a device cannot be shut down anymore but only rebooted.
   virtual void AddShutdownPolicyObserver(ShutdownPolicyObserver* observer);
 
   virtual void RemoveShutdownPolicyObserver(ShutdownPolicyObserver* observer);
 
   // Determines whether the device is automatically rebooted when shut down as
   // specified by the device policy |DeviceRebootOnShutdown|. This function
-  // asynchronously calls |callback| once a trusted policy becomes available.
-  virtual void ShouldRebootOnShutdown(const RebootOnShutdownCallback& callback);
+  // notifies the shutdown policy observers added above once a trusted policy
+  // becomes available.
+  virtual void CheckIfRebootOnShutdown();
 
   // Returns VPNDelegate. May return nullptr.
   virtual VPNDelegate* GetVPNDelegate() const;
 
   // Creates a system tray item for display rotation lock.
   // TODO(jamescook): Remove this when mus has support for display management
   // and we have a DisplayManager equivalent. See http://crbug.com/548429
   virtual std::unique_ptr<SystemTrayItem> CreateRotationLockTrayItem(
       SystemTray* tray);
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_SYSTEM_TRAY_SYSTEM_TRAY_DELEGATE_H_