Virtual destructors should have virtual keyword.

chrome/browser/ui/webui/history2_ui.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_UI_WEBUI_HISTORY2_UI_H_
 #define CHROME_BROWSER_UI_WEBUI_HISTORY2_UI_H_
 #pragma once
 
 #include <string>
 
@@ skipping 14 matching lines @@
 
   // Called when the network layer has requested a resource underneath
   // the path we registered.
   virtual void StartDataRequest(const std::string& path,
                                 bool is_incognito,
                                 int request_id);
 
   virtual std::string GetMimeType(const std::string&) const;
 
  private:
-  ~HistoryUIHTMLSource2() {}
+  virtual ~HistoryUIHTMLSource2() {}
 
   DISALLOW_COPY_AND_ASSIGN(HistoryUIHTMLSource2);
 };
 
 // The handler for Javascript messages related to the "history" view.
 class BrowsingHistoryHandler2 : public WebUIMessageHandler {
  public:
   BrowsingHistoryHandler2();
   virtual ~BrowsingHistoryHandler2();
 
@@ skipping 48 matching lines @@
   // Return the URL for a given search term.
   static const GURL GetHistoryURLWithSearchText(const string16& text);
 
   static RefCountedMemory* GetFaviconResourceBytes();
 
  private:
   DISALLOW_COPY_AND_ASSIGN(HistoryUI2);
 };
 
 #endif  // CHROME_BROWSER_UI_WEBUI_HISTORY2_UI_H_