Standardize usage of virtual/override/final 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 7836dd75a2c4995b660c454768a4f3301dc0f7ef..d46431b798fe7834daab7787ba63f8439b177666 100644
--- a/cc/animation/scrollbar_animation_controller_thinning_unittest.cc
+++ b/cc/animation/scrollbar_animation_controller_thinning_unittest.cc
@@ -22,11 +22,11 @@ class ScrollbarAnimationControllerThinningTest
   ScrollbarAnimationControllerThinningTest()
       : host_impl_(&proxy_, &shared_bitmap_manager_) {}
 
-  virtual void PostDelayedScrollbarFade(const base::Closure& start_fade,
-                                        base::TimeDelta delay) override {
+  void PostDelayedScrollbarFade(const base::Closure& start_fade,
+                                base::TimeDelta delay) override {
     start_fade_ = start_fade;
   }
-  virtual void SetNeedsScrollbarAnimationFrame() override {}
+  void SetNeedsScrollbarAnimationFrame() override {}
 
  protected:
   virtual void SetUp() {