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      1 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef CHROMEOS_DBUS_SYSTEM_CLOCK_CLIENT_H_
      6 #define CHROMEOS_DBUS_SYSTEM_CLOCK_CLIENT_H_
      7 
      8 #include "base/observer_list.h"
      9 #include "chromeos/chromeos_export.h"
     10 #include "chromeos/dbus/dbus_client_implementation_type.h"
     11 
     12 namespace dbus {
     13 class Bus;
     14 }  // namespace
     15 
     16 namespace chromeos {
     17 
     18 // SystemClockClient is used to communicate with the system clock.
     19 class CHROMEOS_EXPORT SystemClockClient {
     20  public:
     21   // Interface for observing changes from the system clock.
     22   class Observer {
     23    public:
     24     // Called when the status is updated.
     25     virtual void SystemClockUpdated() {}
     26    protected:
     27     virtual ~Observer() {}
     28   };
     29 
     30   virtual ~SystemClockClient();
     31 
     32   // Adds and removes the observer.
     33   virtual void AddObserver(Observer* observer) = 0;
     34   virtual void RemoveObserver(Observer* observer) = 0;
     35   // Returns true if this object has the given observer.
     36   virtual bool HasObserver(Observer* observer) = 0;
     37 
     38   // Creates the instance.
     39   static SystemClockClient* Create(DBusClientImplementationType type,
     40                                    dbus::Bus* bus);
     41 
     42  protected:
     43   // Create() should be used instead.
     44   SystemClockClient();
     45 
     46  private:
     47   DISALLOW_COPY_AND_ASSIGN(SystemClockClient);
     48 };
     49 
     50 }  // namespace chromeos
     51 
     52 #endif  // CHROMEOS_DBUS_SYSTEM_CLOCK_CLIENT_H_
     53