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

base/prefs/pref_change_registrar_unittest.cc

Index: base/prefs/pref_change_registrar_unittest.cc
diff --git a/base/prefs/pref_change_registrar_unittest.cc b/base/prefs/pref_change_registrar_unittest.cc
index e44908483f403a0281febd3bc315402e0ff7f90c..da425cfad287b231215949c68553fef231393dd8 100644
--- a/base/prefs/pref_change_registrar_unittest.cc
+++ b/base/prefs/pref_change_registrar_unittest.cc
@@ -36,10 +36,10 @@ class MockPrefService : public TestingPrefServiceSimple {
 class PrefChangeRegistrarTest : public testing::Test {
  public:
   PrefChangeRegistrarTest() {}
-  virtual ~PrefChangeRegistrarTest() {}
+  ~PrefChangeRegistrarTest() override {}
 
  protected:
-  virtual void SetUp() override;
+  void SetUp() override;
 
   base::Closure observer() const {
     return base::Bind(&base::DoNothing);