Standardize usage of virtual/override/final specifiers in cc/.

cc/animation/scrollbar_animation_controller_thinning_unittest.cc

Index: cc/animation/scrollbar_animation_controller_thinning_unittest.cc
diff --git a/cc/animation/scrollbar_animation_controller_thinning_unittest.cc b/cc/animation/scrollbar_animation_controller_thinning_unittest.cc
index 74e9517bb65c03585f9e86d215b398e2b4564212..04036ba639550987fb8aee6811c8bf240a661d24 100644
--- a/cc/animation/scrollbar_animation_controller_thinning_unittest.cc
+++ b/cc/animation/scrollbar_animation_controller_thinning_unittest.cc
@@ -29,7 +29,7 @@ class ScrollbarAnimationControllerThinningTest
   void SetNeedsScrollbarAnimationFrame() override {}
 
  protected:
-  virtual void SetUp() {
+  void SetUp() override {
     scoped_ptr<LayerImpl> scroll_layer =
         LayerImpl::Create(host_impl_.active_tree(), 1);
     clip_layer_ = LayerImpl::Create(host_impl_.active_tree(), 3);