C++11 override style change for athena

chromeos/dbus/update_engine_client.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 CHROMEOS_DBUS_UPDATE_ENGINE_CLIENT_H_
 #define CHROMEOS_DBUS_UPDATE_ENGINE_CLIENT_H_
 
 #include <string>
 
 #include "base/callback.h"
@@ skipping 45 matching lines @@
   // The result code used for RequestUpdateCheck().
   enum UpdateCheckResult {
     UPDATE_RESULT_SUCCESS,
     UPDATE_RESULT_FAILED,
     UPDATE_RESULT_NOTIMPLEMENTED,
   };
 
   // Interface for observing changes from the update engine.
   class Observer {
    public:
+    virtual ~Observer() {}
+
     // Called when the status is updated.
     virtual void UpdateStatusChanged(const Status& status) {}
   };
 
   virtual ~UpdateEngineClient();
 
   // Adds and removes the observer.
   virtual void AddObserver(Observer* observer) = 0;
   virtual void RemoveObserver(Observer* observer) = 0;
   // Returns true if this object has the given observer.
@@ skipping 66 matching lines @@
   // Create() should be used instead.
   UpdateEngineClient();
 
  private:
   DISALLOW_COPY_AND_ASSIGN(UpdateEngineClient);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROMEOS_DBUS_UPDATE_ENGINE_CLIENT_H_