Standardize usage of virtual/override/final in cc/

cc/layers/contents_scaling_layer.h

Index: cc/layers/contents_scaling_layer.h
diff --git a/cc/layers/contents_scaling_layer.h b/cc/layers/contents_scaling_layer.h
index 3b1f828ca69a299c829528d0846adfb5db81629f..15faa005dfcf3c9aa99433c703ed4d5afd943f9b 100644
--- a/cc/layers/contents_scaling_layer.h
+++ b/cc/layers/contents_scaling_layer.h
@@ -14,17 +14,17 @@ namespace cc {
 // The content bounds are determined by bounds and scale of the contents.
 class CC_EXPORT ContentsScalingLayer : public Layer {
  public:
-  virtual void CalculateContentsScale(float ideal_contents_scale,
-                                      float* contents_scale_x,
-                                      float* contents_scale_y,
-                                      gfx::Size* content_bounds) override;
+  void CalculateContentsScale(float ideal_contents_scale,
+                              float* contents_scale_x,
+                              float* contents_scale_y,
+                              gfx::Size* content_bounds) override;
 
-  virtual bool Update(ResourceUpdateQueue* queue,
-                      const OcclusionTracker<Layer>* occlusion) override;
+  bool Update(ResourceUpdateQueue* queue,
+              const OcclusionTracker<Layer>* occlusion) override;
 
  protected:
   ContentsScalingLayer();
-  virtual ~ContentsScalingLayer();
+  ~ContentsScalingLayer() override;
 
   gfx::Size ComputeContentBoundsForScale(float scale_x, float scale_y) const;