GTTF: Add missing virtual destructors.

chrome/browser/extensions/activity_log.h

 // Copyright (c) 2012 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_ACTIVITY_LOG_H_
 #define CHROME_BROWSER_EXTENSIONS_ACTIVITY_LOG_H_
 
 #include <map>
 #include <string>
 #include <vector>
@@ skipping 28 matching lines @@
     ACTIVITY_CONTENT_SCRIPT        // Content script is executing.
   };
 
   // Observers can listen for activity events.
   class Observer {
    public:
     virtual void OnExtensionActivity(
         const Extension* extension,
         Activity activity,
         const std::string& message) = 0;
+
+   protected:
+    virtual ~Observer() { }
   };
 
   // ActivityLog is a singleton, so don't instantiate it with the constructor;
   // use GetInstance instead.
   static ActivityLog* GetInstance(Profile* profile);
 
   // Currently, we only want to record actions if the user has opted in to the
   // ActivityLog feature.
   bool IsLoggingEnabled();
 
@@ skipping 121 matching lines @@
   virtual bool ServiceRedirectedInIncognito() const OVERRIDE;
 
   DISALLOW_COPY_AND_ASSIGN(ActivityLogFactory);
 };
 
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_ACTIVITY_LOG_H_