Standardize usage of virtual/override/final in extensions/

extensions/renderer/runtime_custom_bindings.h

 // Copyright 2014 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 EXTENSIONS_RENDERER_RUNTIME_CUSTOM_BINDINGS_H_
 #define EXTENSIONS_RENDERER_RUNTIME_CUSTOM_BINDINGS_H_
 
 #include "base/compiler_specific.h"
 #include "extensions/renderer/object_backed_native_handler.h"
 #include "v8/include/v8.h"
 
 namespace extensions {
 
 // The native component of custom bindings for the chrome.runtime API.
 class RuntimeCustomBindings : public ObjectBackedNativeHandler {
  public:
   explicit RuntimeCustomBindings(ScriptContext* context);
 
-  virtual ~RuntimeCustomBindings();
+  ~RuntimeCustomBindings() override;
 
   // Creates a new messaging channel to the given extension.
   void OpenChannelToExtension(const v8::FunctionCallbackInfo<v8::Value>& args);
 
   // Creates a new messaging channels for the specified native application.
   void OpenChannelToNativeApp(const v8::FunctionCallbackInfo<v8::Value>& args);
 
  private:
   void GetManifest(const v8::FunctionCallbackInfo<v8::Value>& args);
   void GetExtensionViews(const v8::FunctionCallbackInfo<v8::Value>& args);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_RENDERER_RUNTIME_CUSTOM_BINDINGS_H_