Standardize usage of virtual/override/final in cc/

cc/layers/io_surface_layer.h

 // Copyright 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 CC_LAYERS_IO_SURFACE_LAYER_H_
 #define CC_LAYERS_IO_SURFACE_LAYER_H_
 
 #include "cc/base/cc_export.h"
 #include "cc/layers/layer.h"
 
 namespace cc {
 
 class CC_EXPORT IOSurfaceLayer : public Layer {
  public:
   static scoped_refptr<IOSurfaceLayer> Create();
 
   void SetIOSurfaceProperties(uint32_t io_surface_id, const gfx::Size& size);
 
-  virtual scoped_ptr<LayerImpl> CreateLayerImpl(LayerTreeImpl* tree_impl)
-      override;
-  virtual void PushPropertiesTo(LayerImpl* layer) override;
-  virtual bool Update(ResourceUpdateQueue* queue,
-                      const OcclusionTracker<Layer>* occlusion) override;
+  scoped_ptr<LayerImpl> CreateLayerImpl(LayerTreeImpl* tree_impl) override;
+  void PushPropertiesTo(LayerImpl* layer) override;
+  bool Update(ResourceUpdateQueue* queue,
+              const OcclusionTracker<Layer>* occlusion) override;
 
  protected:
-  virtual bool HasDrawableContent() const override;
+  bool HasDrawableContent() const override;
   IOSurfaceLayer();
 
  private:
-  virtual ~IOSurfaceLayer();
+  ~IOSurfaceLayer() override;
 
   uint32_t io_surface_id_;
   gfx::Size io_surface_size_;
 
   DISALLOW_COPY_AND_ASSIGN(IOSurfaceLayer);
 };
 
 }  // namespace cc
 #endif  // CC_LAYERS_IO_SURFACE_LAYER_H_