Standardize usage of virtual/override/final specifiers.

chrome/browser/dom_distiller/dom_distiller_viewer_source_browsertest.cc

 // Copyright 2014 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 <string.h>
 
 #include "base/command_line.h"
 #include "base/guid.h"
 #include "base/path_service.h"
 #include "base/strings/utf_string_conversions.h"
@@ skipping 62 matching lines @@
     page->set_url(page_url);
   }
   return entry;
 }
 
 }  // namespace
 
 class DomDistillerViewerSourceBrowserTest : public InProcessBrowserTest {
  public:
   DomDistillerViewerSourceBrowserTest() {}
-  virtual ~DomDistillerViewerSourceBrowserTest() {}
+  ~DomDistillerViewerSourceBrowserTest() override {}
 
   void SetUpOnMainThread() override {
     database_model_ = new FakeDB<ArticleEntry>::EntryMap;
   }
 
   void TearDownOnMainThread() override { delete database_model_; }
 
   void SetUpCommandLine(CommandLine* command_line) override {
     command_line->AppendSwitch(switches::kEnableDomDistiller);
   }
@@ skipping 261 matching lines @@
   EXPECT_EQ("dark sans-serif", result);
 
   distilled_page_prefs->SetFontFamily(DistilledPagePrefs::SERIF);
   base::RunLoop().RunUntilIdle();
   EXPECT_TRUE(
       content::ExecuteScriptAndExtractString(contents, kGetBodyClass, &result));
   EXPECT_EQ("dark serif", result);
 }
 
 }  // namespace dom_distiller