Virtual destructors should have virtual keyword.

chrome/browser/extensions/extension_tts_api.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_EXTENSIONS_EXTENSION_TTS_API_H_
 #define CHROME_BROWSER_EXTENSIONS_EXTENSION_TTS_API_H_
 
 #include <queue>
 #include <string>
 
@@ skipping 187 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionTtsController);
 };
 
 //
 // Extension API function definitions
 //
 
 class ExtensionTtsSpeakFunction : public AsyncExtensionFunction {
  private:
-  ~ExtensionTtsSpeakFunction() {}
+  virtual ~ExtensionTtsSpeakFunction() {}
   virtual bool RunImpl();
   void SpeechFinished();
   Utterance* utterance_;
   DECLARE_EXTENSION_FUNCTION_NAME("experimental.tts.speak")
 };
 
 class ExtensionTtsStopSpeakingFunction : public SyncExtensionFunction {
  private:
-  ~ExtensionTtsStopSpeakingFunction() {}
+  virtual ~ExtensionTtsStopSpeakingFunction() {}
   virtual bool RunImpl();
   DECLARE_EXTENSION_FUNCTION_NAME("experimental.tts.stop")
 };
 
 class ExtensionTtsIsSpeakingFunction : public SyncExtensionFunction {
  private:
-  ~ExtensionTtsIsSpeakingFunction() {}
+  virtual ~ExtensionTtsIsSpeakingFunction() {}
   virtual bool RunImpl();
   DECLARE_EXTENSION_FUNCTION_NAME("experimental.tts.isSpeaking")
 };
 
 class ExtensionTtsSpeakCompletedFunction : public SyncExtensionFunction {
  private:
-  ~ExtensionTtsSpeakCompletedFunction() {}
+  virtual ~ExtensionTtsSpeakCompletedFunction() {}
   virtual bool RunImpl();
   DECLARE_EXTENSION_FUNCTION_NAME("experimental.tts.speakCompleted")
 };
 
 #endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_TTS_API_H_