Standardize usage of virtual/override/final specifiers in webkit/.

webkit/common/gpu/context_provider_web_context.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 WEBKIT_COMMON_GPU_CONTEXT_PROVIDER_WEB_CONTEXT_H_
 #define WEBKIT_COMMON_GPU_CONTEXT_PROVIDER_WEB_CONTEXT_H_
 
 #include "cc/output/context_provider.h"
 
 namespace blink { class WebGraphicsContext3D; }
 
 namespace webkit {
 namespace gpu {
 
 class ContextProviderWebContext : public cc::ContextProvider {
  public:
   virtual blink::WebGraphicsContext3D* WebContext3D() = 0;
 
  protected:
-  virtual ~ContextProviderWebContext() {}
+  ~ContextProviderWebContext() override {}
 };
 
 }  // namespace gpu
 }  // namespace webkit
 
 #endif  // WEBKIT_COMMON_GPU_CONTEXT_PROVIDER_WEB_CONTEXT_H_