Update {virtual,override,final} to follow C++11 style in ash.

ash/system/chromeos/audio/audio_detailed_view.h

Index: ash/system/chromeos/audio/audio_detailed_view.h
diff --git a/ash/system/chromeos/audio/audio_detailed_view.h b/ash/system/chromeos/audio/audio_detailed_view.h
index 9995fe7d107980372313a64b0a0260a52da37cee..f150b92cf2a178d457b53e20665a5024814df1e5 100644
--- a/ash/system/chromeos/audio/audio_detailed_view.h
+++ b/ash/system/chromeos/audio/audio_detailed_view.h
@@ -26,7 +26,7 @@ class AudioDetailedView : public TrayDetailsView,
  public:
   AudioDetailedView(SystemTrayItem* owner, user::LoginStatus login);
 
-  virtual ~AudioDetailedView();
+  ~AudioDetailedView() override;
 
   void Update();
 
@@ -44,7 +44,7 @@ class AudioDetailedView : public TrayDetailsView,
   void UpdateAudioDevices();
 
   // Overridden from ViewClickListener.
-  virtual void OnViewClicked(views::View* sender) override;
+  void OnViewClicked(views::View* sender) override;
 
   user::LoginStatus login_;