Standardize usage of virtual/override/final in extensions/

extensions/browser/warning_service_unittest.cc

 // Copyright (c) 2012 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 "extensions/browser/warning_service.h"
 
 #include "content/public/test/test_browser_context.h"
 #include "extensions/browser/extensions_test.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace extensions {
 
 namespace {
 
 class TestWarningService : public WarningService {
  public:
   explicit TestWarningService(content::BrowserContext* browser_context)
       : WarningService(browser_context) {
   }
-  virtual ~TestWarningService() {}
+  ~TestWarningService() override {}
 
   void AddWarning(const Warning& warning) {
     WarningSet warnings;
     warnings.insert(warning);
     AddWarnings(warnings);
   }
 };
 
 class MockObserver : public WarningService::Observer {
  public:
@@ skipping 76 matching lines @@
       warning_service.GetWarningTypesAffectingExtension(ext1_id);
   EXPECT_EQ(0u, existing_warnings.size());
   existing_warnings =
       warning_service.GetWarningTypesAffectingExtension(ext2_id);
   EXPECT_EQ(0u, existing_warnings.size());
 
   warning_service.RemoveObserver(&observer);
 }
 
 }  // namespace extensions