Clean up virtual functions in css/

Source/core/css/RemoteFontFaceSource.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 RemoteFontFaceSource_h
 #define RemoteFontFaceSource_h
 
 #include "core/css/CSSFontFaceSource.h"
 #include "core/fetch/FontResource.h"
 #include "core/fetch/ResourcePtr.h"
 
 namespace blink {
 
 class FontLoader;
 
-class RemoteFontFaceSource : public CSSFontFaceSource, public FontResourceClient {
+class RemoteFontFaceSource final : public CSSFontFaceSource, public FontResourceClient {
 public:
     explicit RemoteFontFaceSource(FontResource*, PassRefPtrWillBeRawPtr<FontLoader>);
     virtual ~RemoteFontFaceSource();
 
     virtual FontResource* resource() override { return m_font.get(); }
     virtual bool isLoading() const override;
     virtual bool isLoaded() const override;
     virtual bool isValid() const override;
 
     void beginLoadIfNeeded() override;
@@ skipping 30 matching lines @@
     };
 
     ResourcePtr<FontResource> m_font;
     RefPtrWillBeMember<FontLoader> m_fontLoader;
     FontLoadHistograms m_histograms;
 };
 
 } // namespace blink
 
 #endif