Update {virtual,override,final} to follow C++11 style in ash.

ash/display/display_manager_unittest.cc

Index: ash/display/display_manager_unittest.cc
diff --git a/ash/display/display_manager_unittest.cc b/ash/display/display_manager_unittest.cc
index e3e7f8c9c16c1c850f760f4b301c584ac578ecd0..ae5c192764b2419ec4d5fba84efac8a88988b5dd 100644
--- a/ash/display/display_manager_unittest.cc
+++ b/ash/display/display_manager_unittest.cc
@@ -1576,14 +1576,10 @@ class FontTestHelper : public test::AshTestBase {
     SetUp();
   }
 
-  virtual ~FontTestHelper() {
-    TearDown();
-  }
+  ~FontTestHelper() override { TearDown(); }
 
   // test::AshTestBase:
-  virtual void TestBody() override {
-    NOTREACHED();
-  }
+  void TestBody() override { NOTREACHED(); }
 
  private:
   DISALLOW_COPY_AND_ASSIGN(FontTestHelper);