Fix virtual/override/final usage in Source/core/{fetch,loader,streams,xmlhttprequest}/.

Source/core/fetch/DocumentResourceReference.h

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 16 matching lines @@
 #define DocumentResourceReference_h
 
 #include "core/fetch/DocumentResource.h"
 #include "core/fetch/ResourcePtr.h"
 
 namespace blink {
 
 class DocumentResourceReference final : public DocumentResourceClient {
 public:
     DocumentResourceReference(DocumentResource* document) : m_document(document) { m_document->addClient(this); }
-    virtual ~DocumentResourceReference() { m_document->removeClient(this); }
+    ~DocumentResourceReference() override { m_document->removeClient(this); }
     DocumentResource* document() { return m_document.get(); }
 private:
     ResourcePtr<DocumentResource> m_document;
 };
 
 };
 
 #endif