Virtual destructors should have virtual keyword.

chrome/browser/autocomplete/history_contents_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.
 
 #ifndef CHROME_BROWSER_AUTOCOMPLETE_HISTORY_CONTENTS_PROVIDER_H_
 #define CHROME_BROWSER_AUTOCOMPLETE_HISTORY_CONTENTS_PROVIDER_H_
 #pragma once
 
 #include "chrome/browser/autocomplete/history_provider.h"
 #include "chrome/browser/history/history.h"
@@ skipping 17 matching lines @@
                           Profile* profile,
                           bool body_only);
 
   // As necessary asks the history service for the relevant results. When
   // done SetResults is invoked.
   virtual void Start(const AutocompleteInput& input,
                      bool minimal_changes) OVERRIDE;
   virtual void Stop() OVERRIDE;
 
  private:
-  ~HistoryContentsProvider();
+  virtual ~HistoryContentsProvider();
 
   void QueryComplete(HistoryService::Handle handle,
                      history::QueryResults* results);
 
   // Converts each MatchingPageResult in results_ to an AutocompleteMatch and
   // adds it to matches_.
   void ConvertResults();
 
   // Creates and returns an AutocompleteMatch from a MatchingPageResult.
   AutocompleteMatch ResultToMatch(const history::URLResult& result,
@@ skipping 47 matching lines @@
   // Whether results_ is valid (so we can tell invalid apart from empty).
   bool have_results_;
 
   // Current query string.
   string16 query_;
 
   DISALLOW_COPY_AND_ASSIGN(HistoryContentsProvider);
 };
 
 #endif  // CHROME_BROWSER_AUTOCOMPLETE_HISTORY_CONTENTS_PROVIDER_H_