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

chromeos/audio/cras_audio_handler.h

Index: chromeos/audio/cras_audio_handler.h
diff --git a/chromeos/audio/cras_audio_handler.h b/chromeos/audio/cras_audio_handler.h
index 73b0f9fd4edf2518f5ac0d5b1df6a8562f208990..e16161f0c27c83948a012c46c716c247deca1500 100644
--- a/chromeos/audio/cras_audio_handler.h
+++ b/chromeos/audio/cras_audio_handler.h
@@ -191,22 +191,22 @@ class CHROMEOS_EXPORT CrasAudioHandler : public CrasAudioClient::Observer,
  protected:
   explicit CrasAudioHandler(
       scoped_refptr<AudioDevicesPrefHandler> audio_pref_handler);
-  virtual ~CrasAudioHandler();
+  ~CrasAudioHandler() override;
 
  private:
   friend class CrasAudioHandlerTest;
 
   // CrasAudioClient::Observer overrides.
-  virtual void AudioClientRestarted() override;
-  virtual void NodesChanged() override;
-  virtual void ActiveOutputNodeChanged(uint64 node_id) override;
-  virtual void ActiveInputNodeChanged(uint64 node_id) override;
+  void AudioClientRestarted() override;
+  void NodesChanged() override;
+  void ActiveOutputNodeChanged(uint64 node_id) override;
+  void ActiveInputNodeChanged(uint64 node_id) override;
 
   // AudioPrefObserver overrides.
-  virtual void OnAudioPolicyPrefChanged() override;
+  void OnAudioPolicyPrefChanged() override;
 
   // SessionManagerClient::Observer overrides.
-  virtual void EmitLoginPromptVisibleCalled() override;
+  void EmitLoginPromptVisibleCalled() override;
 
   // Sets the active audio output/input node to the node with |node_id|.
   // If |notify|, notifies Active*NodeChange.