Standardize usage of virtual/override/final in cc/

cc/layers/heads_up_display_layer.h

Index: cc/layers/heads_up_display_layer.h
diff --git a/cc/layers/heads_up_display_layer.h b/cc/layers/heads_up_display_layer.h
index 22dcec8011cc0ad4e8553e54d4c1f6ea4fe6da00..7ca09925102e757981be06eee4cf4f37dac3730f 100644
--- a/cc/layers/heads_up_display_layer.h
+++ b/cc/layers/heads_up_display_layer.h
@@ -20,16 +20,14 @@ class CC_EXPORT HeadsUpDisplayLayer : public ContentsScalingLayer {
   void PrepareForCalculateDrawProperties(
       const gfx::Size& device_viewport, float device_scale_factor);
 
-
-  virtual scoped_ptr<LayerImpl> CreateLayerImpl(LayerTreeImpl* tree_impl)
-      override;
+  scoped_ptr<LayerImpl> CreateLayerImpl(LayerTreeImpl* tree_impl) override;
 
  protected:
   HeadsUpDisplayLayer();
-  virtual bool HasDrawableContent() const override;
+  bool HasDrawableContent() const override;
 
  private:
-  virtual ~HeadsUpDisplayLayer();
+  ~HeadsUpDisplayLayer() override;
 
   DISALLOW_COPY_AND_ASSIGN(HeadsUpDisplayLayer);
 };