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

Source/core/fetch/ImageResourceClient.h

 /*
     Copyright (C) 1998 Lars Knoll (knoll@mpi-hd.mpg.de)
     Copyright (C) 2001 Dirk Mueller <mueller@kde.org>
     Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
     Copyright (C) 2004, 2005, 2006, 2007 Apple Inc. All rights reserved.
 
     This library is free software; you can redistribute it and/or
     modify it under the terms of the GNU Library General Public
     License as published by the Free Software Foundation; either
     version 2 of the License, or (at your option) any later version.
@@ skipping 16 matching lines @@
 #include "core/fetch/ResourceClient.h"
 #include "platform/graphics/ImageAnimationPolicy.h"
 
 namespace blink {
 
 class ImageResource;
 class IntRect;
 
 class CORE_EXPORT ImageResourceClient : public ResourceClient {
 public:
-    virtual ~ImageResourceClient() { }
+    ~ImageResourceClient() override {}
     static ResourceClientType expectedType() { return ImageType; }
-    virtual ResourceClientType resourceClientType() const override final { return expectedType(); }
+    ResourceClientType resourceClientType() const final { return expectedType(); }
 
     // Called whenever a frame of an image changes, either because we got more data from the network or
     // because we are animating. If not null, the IntRect is the changed rect of the image.
     virtual void imageChanged(ImageResource*, const IntRect* = 0) { }
 
     // Called to find out if this client wants to actually display the image. Used to tell when we
     // can halt animation. Content nodes that hold image refs for example would not render the image,
     // but LayoutImages would (assuming they have visibility: visible and their layout tree isn't hidden
     // e.g., in the b/f cache or in a background tab).
     virtual bool willRenderImage(ImageResource*) { return false; }
 
     // Called to get imageAnimation policy from settings
     virtual bool getImageAnimationPolicy(ImageResource*, ImageAnimationPolicy&) { return false; }
 };
 
 }
 
 #endif