Standardize usage of virtual/override/final in cc/

cc/layers/surface_layer.h

 // Copyright 2014 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 CC_LAYERS_SURFACE_LAYER_H_
 #define CC_LAYERS_SURFACE_LAYER_H_
 
 #include "cc/base/cc_export.h"
 #include "cc/layers/layer.h"
 #include "cc/surfaces/surface_id.h"
 
 namespace cc {
 
 // A layer that renders a surface referencing the output of another compositor
 // instance or client.
 class CC_EXPORT SurfaceLayer : public Layer {
  public:
   static scoped_refptr<SurfaceLayer> Create();
 
   void SetSurfaceId(SurfaceId surface_id);
 
   // Layer overrides.
-  virtual scoped_ptr<LayerImpl> CreateLayerImpl(LayerTreeImpl* tree_impl)
-      override;
-  virtual void PushPropertiesTo(LayerImpl* layer) override;
+  scoped_ptr<LayerImpl> CreateLayerImpl(LayerTreeImpl* tree_impl) override;
+  void PushPropertiesTo(LayerImpl* layer) override;
 
  protected:
   SurfaceLayer();
-  virtual bool HasDrawableContent() const override;
+  bool HasDrawableContent() const override;
 
  private:
-  virtual ~SurfaceLayer();
+  ~SurfaceLayer() override;
 
   SurfaceId surface_id_;
 
   DISALLOW_COPY_AND_ASSIGN(SurfaceLayer);
 };
 
 }  // namespace cc
 
 #endif  // CC_LAYERS_SURFACE_LAYER_H_