Standardize usage of virtual/override/final specifiers.

content/renderer/render_thread_impl_unittest.cc

Index: content/renderer/render_thread_impl_unittest.cc
diff --git a/content/renderer/render_thread_impl_unittest.cc b/content/renderer/render_thread_impl_unittest.cc
index 262b21ad15099ccaa0ae91bfddcfa0935040a9a3..659eba4410ef8f447565d639ce88aca3d93ccbd3 100644
--- a/content/renderer/render_thread_impl_unittest.cc
+++ b/content/renderer/render_thread_impl_unittest.cc
@@ -14,9 +14,10 @@ class RenderThreadImplUnittest : public testing::Test {
   RenderThreadImplUnittest()
       : kCustomizableHistogram_("Histogram1"),
         kNormalHistogram_("Histogram2") {}
-  virtual ~RenderThreadImplUnittest() {}
+  ~RenderThreadImplUnittest() override {}
+
  protected:
-  virtual void SetUp() override {
+  void SetUp() override {
     histogram_customizer_.custom_histograms_.clear();
     histogram_customizer_.custom_histograms_.insert(kCustomizableHistogram_);
   }