Virtual destructors should have virtual keyword.

chrome/browser/translate/translate_tab_helper.h

 // Copyright (c) 2011 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.
 
 #ifndef CHROME_BROWSER_TRANSLATE_TRANSLATE_TAB_HELPER_H_
 #define CHROME_BROWSER_TRANSLATE_TRANSLATE_TAB_HELPER_H_
 #pragma once
 
 #include "chrome/browser/tab_contents/language_state.h"
 #include "chrome/common/translate_errors.h"
 #include "content/browser/tab_contents/tab_contents_observer.h"
 
 class TranslateTabHelper : public TabContentsObserver {
  public:
   explicit TranslateTabHelper(TabContents* tab_contents);
-  ~TranslateTabHelper();
+  virtual ~TranslateTabHelper();
 
   LanguageState& language_state() { return language_state_; }
 
  private:
   // TabContentsObserver implementation.
   virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
   virtual void DidNavigateAnyFramePostCommit(
       const NavigationController::LoadCommittedDetails& details,
       const ViewHostMsg_FrameNavigate_Params& params) OVERRIDE;
 
   void OnLanguageDetermined(const std::string& language,
                             bool page_translatable);
   void OnPageTranslated(int32 page_id,
                         const std::string& original_lang,
                         const std::string& translated_lang,
                         TranslateErrors::Type error_type);
 
   // Information about the language the page is in and has been translated to.
   LanguageState language_state_;
 
   DISALLOW_COPY_AND_ASSIGN(TranslateTabHelper);
 };
 
 #endif  // CHROME_BROWSER_TRANSLATE_TRANSLATE_TAB_HELPER_H_