Standardize usage of virtual/override/final in chrome/browser/plugins

chrome/browser/plugins/plugin_installer_observer.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_PLUGINS_PLUGIN_INSTALLER_OBSERVER_H_
 #define CHROME_BROWSER_PLUGINS_PLUGIN_INSTALLER_OBSERVER_H_
 
 #include <string>
 
 class PluginInstaller;
@@ skipping 17 matching lines @@
   // Weak pointer; Owned by PluginFinder, which is a singleton.
   PluginInstaller* installer_;
 };
 
 // A WeakPluginInstallerObserver is like a weak pointer to the installer, in the
 // sense that if only weak observers are left, we don't need to show
 // installation UI anymore.
 class WeakPluginInstallerObserver : public PluginInstallerObserver {
  public:
   explicit WeakPluginInstallerObserver(PluginInstaller* installer);
-  virtual ~WeakPluginInstallerObserver();
+  ~WeakPluginInstallerObserver() override;
 
  private:
   friend class PluginInstaller;
 
   virtual void OnlyWeakObserversLeft();
 };
 
 #endif  // CHROME_BROWSER_PLUGINS_PLUGIN_INSTALLER_OBSERVER_H_