Standardize usage of virtual/override/final in cc/

cc/layers/io_surface_layer_impl.h

Index: cc/layers/io_surface_layer_impl.h
diff --git a/cc/layers/io_surface_layer_impl.h b/cc/layers/io_surface_layer_impl.h
index d6b6625eebfabff3cc0f3ecb6cfde5463f601cf9..17b70936f713fae1601341be5d7050301a496657 100644
--- a/cc/layers/io_surface_layer_impl.h
+++ b/cc/layers/io_surface_layer_impl.h
@@ -19,28 +19,27 @@ class CC_EXPORT IOSurfaceLayerImpl : public LayerImpl {
                                                int id) {
     return make_scoped_ptr(new IOSurfaceLayerImpl(tree_impl, id));
   }
-  virtual ~IOSurfaceLayerImpl();
+  ~IOSurfaceLayerImpl() override;
 
   void SetIOSurfaceProperties(unsigned io_surface_id, const gfx::Size& size);
 
-  virtual scoped_ptr<LayerImpl> CreateLayerImpl(LayerTreeImpl* tree_impl)
-      override;
-  virtual void PushPropertiesTo(LayerImpl* layer_tree_impl) override;
+  scoped_ptr<LayerImpl> CreateLayerImpl(LayerTreeImpl* tree_impl) override;
+  void PushPropertiesTo(LayerImpl* layer_tree_impl) override;
 
-  virtual void AppendQuads(RenderPass* render_pass,
-                           const Occlusion& occlusion_in_content_space,
-                           AppendQuadsData* append_quads_data) override;
+  void AppendQuads(RenderPass* render_pass,
+                   const Occlusion& occlusion_in_content_space,
+                   AppendQuadsData* append_quads_data) override;
 
-  virtual bool WillDraw(DrawMode draw_mode,
-                        ResourceProvider* resource_provider) override;
-  virtual void ReleaseResources() override;
+  bool WillDraw(DrawMode draw_mode,
+                ResourceProvider* resource_provider) override;
+  void ReleaseResources() override;
 
  private:
   IOSurfaceLayerImpl(LayerTreeImpl* tree_impl, int id);
 
   void DestroyResource();
 
-  virtual const char* LayerTypeAsString() const override;
+  const char* LayerTypeAsString() const override;
 
   unsigned io_surface_id_;
   gfx::Size io_surface_size_;