Standardize usage of virtual/override/final specifiers.

ash/system/date/date_view_unittest.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ash/system/date/date_view.h"
 
 #include "ash/test/ash_test_base.h"
 #include "ui/views/controls/label.h"
 
 namespace ash {
 namespace tray {
 
 class TimeViewTest : public ash::test::AshTestBase {
  public:
   TimeViewTest() {}
-  virtual ~TimeViewTest() {}
+  ~TimeViewTest() override {}
 
   TimeView* time_view() { return time_view_.get(); }
 
   // Access to private fields of |time_view_|.
   views::Label* horizontal_label() {
     return time_view_->horizontal_label_.get();
   }
   views::Label* vertical_label_hours() {
     return time_view_->vertical_label_hours_.get();
   }
@@ skipping 28 matching lines @@
 
   // Switching back to horizontal updates the labels again.
   time_view()->UpdateClockLayout(TrayDate::HORIZONTAL_CLOCK);
   EXPECT_EQ(time_view(), horizontal_label()->parent());
   EXPECT_FALSE(vertical_label_hours()->parent());
   EXPECT_FALSE(vertical_label_minutes()->parent());
 }
 
 }  // namespace tray
 }  // namespace ash