Make ClientHintsPreferences class work like a class.

Source/core/loader/FrameLoader.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2008 Alp Toker <alp@atoker.com>
  * Copyright (C) Research In Motion Limited 2009. All rights reserved.
  * Copyright (C) 2011 Kris Jordan <krisjordan@gmail.com>
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ skipping 422 matching lines @@
     ASSERT(m_frame);
     ASSERT(m_frame->document());
     ASSERT(m_frame->document()->fetcher());
     m_frame->document()->setReadyState(Document::Loading);
 
     if (dispatch)
         dispatchDidClearDocumentOfWindowObject();
 
     m_frame->document()->initContentSecurityPolicy(m_documentLoader ? m_documentLoader->releaseContentSecurityPolicy() : ContentSecurityPolicy::create());
     if (m_documentLoader)
-        m_frame->document()->setClientHintsPreferences(m_documentLoader->clientHintsPreferences());
+        m_frame->document()->clientHintsPreferences().updateFrom(m_documentLoader->clientHintsPreferences());
 
     Settings* settings = m_frame->document()->settings();
     if (settings) {
         m_frame->document()->fetcher()->setImagesEnabled(settings->imagesEnabled());
         m_frame->document()->fetcher()->setAutoLoadImages(settings->loadsImagesAutomatically());
     }
 
     if (m_documentLoader) {
         const AtomicString& dnsPrefetchControl = m_documentLoader->response().httpHeaderField("X-DNS-Prefetch-Control");
         if (!dnsPrefetchControl.isEmpty())
@@ skipping 1060 matching lines @@
     // FIXME: We need a way to propagate insecure requests policy flags to
     // out-of-process frames. For now, we'll always use default behavior.
     if (!parentFrame->isLocalFrame())
         return nullptr;
 
     ASSERT(toLocalFrame(parentFrame)->document());
     return toLocalFrame(parentFrame)->document()->insecureNavigationsToUpgrade();
 }
 
 } // namespace blink