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

Source/core/fetch/MemoryCache.h

 /*
     Copyright (C) 1998 Lars Knoll (knoll@mpi-hd.mpg.de)
     Copyright (C) 2001 Dirk Mueller <mueller@kde.org>
     Copyright (C) 2004, 2005, 2006, 2007, 2008 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 205 matching lines @@
     size_t minDeadCapacity() const { return m_minDeadCapacity; }
     size_t maxDeadCapacity() const { return m_maxDeadCapacity; }
     size_t capacity() const { return m_capacity; }
     size_t liveSize() const { return m_liveSize; }
     size_t deadSize() const { return m_deadSize; }
 
     // Exposed for testing
     MemoryCacheLiveResourcePriority priority(Resource*) const;
 
     // TaskObserver implementation
-    virtual void willProcessTask() override;
-    virtual void didProcessTask() override;
+    void willProcessTask() override;
+    void didProcessTask() override;
 
     void pruneAll();
 
     void updateFramePaintTimestamp();
 
 private:
     enum PruneStrategy {
         // Automatically decide how much to prune.
         AutomaticPrune,
         // Maximally prune resources.
@@ skipping 84 matching lines @@
 // Returns the global cache.
 CORE_EXPORT MemoryCache* memoryCache();
 
 // Sets the global cache, used to swap in a test instance. Returns the old
 // MemoryCache object.
 CORE_EXPORT MemoryCache* replaceMemoryCacheForTesting(MemoryCache*);
 
 }
 
 #endif