Declarative resource hints go through mojo IPC to //content

third_party/WebKit/Source/core/html/HTMLAnchorElement.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Simon Hausmann <hausmann@kde.org>
  * Copyright (C) 2003, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
  *           (C) 2006 Graham Dennis (graham.dennis@gmail.com)
  *
  * 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
@@ skipping 180 matching lines @@
         }
         if (wasLink && !isLink() && adjustedFocusedElementInTreeScope() == this) {
             // We might want to call blur(), but it's dangerous to dispatch
             // events here.
             document().setNeedsFocusedElementCheck();
         }
         if (isLink()) {
             String parsedURL = stripLeadingAndTrailingHTMLSpaces(value);
             if (document().isDNSPrefetchEnabled()) {
                 if (protocolIs(parsedURL, "http") || protocolIs(parsedURL, "https") || parsedURL.startsWith("//"))
-                    prefetchDNS(document().completeURL(parsedURL).host());
+                    prefetchDNS(document().completeURL(parsedURL));
             }
         }
         invalidateCachedVisitedLinkHash();
         logUpdateAttributeIfIsolatedWorldAndInDocument("a", hrefAttr, oldValue, value);
     } else if (name == nameAttr || name == titleAttr) {
         // Do nothing.
     } else if (name == relAttr) {
         setRel(value);
     } else {
         HTMLElement::parseAttribute(name, oldValue, value);
@@ skipping 178 matching lines @@
 }
 
 Node::InsertionNotificationRequest HTMLAnchorElement::insertedInto(ContainerNode* insertionPoint)
 {
     InsertionNotificationRequest request = HTMLElement::insertedInto(insertionPoint);
     logAddElementIfIsolatedWorldAndInDocument("a", hrefAttr);
     return request;
 }
 
 } // namespace blink