Virtual destructors should have virtual keyword.

chrome/browser/autocomplete/search_provider.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.
 //
 // This file contains the Search autocomplete provider.  This provider is
 // responsible for all non-keyword autocomplete entries that start with
 // "Search <engine> for ...", including searching for the current input string,
 // search history, and search suggestions.  An instance of it gets created and
 // managed by the autocomplete controller.
 //
@@ skipping 64 matching lines @@
                                   const net::ResponseCookies& cookies,
                                   const std::string& data);
 
   // ID used in creating URLFetcher for default provider's suggest results.
   static const int kDefaultProviderURLFetcherID;
 
   // ID used in creating URLFetcher for keyword provider's suggest results.
   static const int kKeywordProviderURLFetcherID;
 
  private:
-  ~SearchProvider();
+  virtual ~SearchProvider();
 
   // Manages the providers (TemplateURLs) used by SearchProvider. Two providers
   // may be used:
   // . The default provider. This corresponds to the user's default search
   //   engine. This is always used, except for the rare case of no default
   //   engine.
   // . The keyword provider. This is used if the user has typed in a keyword.
   class Providers {
    public:
     Providers() : default_provider_(NULL), keyword_provider_(NULL) {}
@@ skipping 223 matching lines @@
   // Has FinalizeInstantQuery been invoked since the last |Start|?
   bool instant_finalized_;
 
   // The |suggest_text| parameter passed to FinalizeInstantQuery.
   string16 default_provider_suggest_text_;
 
   DISALLOW_COPY_AND_ASSIGN(SearchProvider);
 };
 
 #endif  // CHROME_BROWSER_AUTOCOMPLETE_SEARCH_PROVIDER_H_