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

Source/core/fetch/MockImageResourceClient.h

 /*
  * Copyright (c) 2013, 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 27 matching lines @@
 namespace blink {
 
 class MockImageResourceClient final : public ImageResourceClient {
 public:
     MockImageResourceClient()
         : m_imageChangedCount(0)
         , m_notifyFinishedCalled(false)
     {
     }
 
-    virtual ~MockImageResourceClient() { }
-    virtual void imageChanged(ImageResource*, const IntRect*) override
+    ~MockImageResourceClient() override {}
+    void imageChanged(ImageResource*, const IntRect*) override
     {
         m_imageChangedCount++;
     }
 
-    virtual void notifyFinished(Resource*) override
+    void notifyFinished(Resource*) override
     {
         ASSERT_FALSE(m_notifyFinishedCalled);
         m_notifyFinishedCalled = true;
     }
 
     int imageChangedCount() const { return m_imageChangedCount; }
     bool notifyFinishedCalled() const { return m_notifyFinishedCalled; }
 
 private:
     int m_imageChangedCount;
     bool m_notifyFinishedCalled;
 };
 
 } // namespace blink
 
 #endif // ImageResourceTest_h