Declarative resource hints go through mojo IPC to //content

third_party/WebKit/Source/core/loader/LinkLoader.cpp

 /*
  * Copyright (C) 2011 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 130 matching lines @@
     if (relAttribute.isDNSPrefetch()) {
         UseCounter::count(document, UseCounter::LinkRelDnsPrefetch);
         if (caller == LinkCalledFromHeader)
             UseCounter::count(document, UseCounter::LinkHeaderDnsPrefetch);
         Settings* settings = document.settings();
         // FIXME: The href attribute of the link element can be in "//hostname" form, and we shouldn't attempt
         // to complete that as URL <https://bugs.webkit.org/show_bug.cgi?id=48857>.
         if (settings && settings->dnsPrefetchingEnabled() && href.isValid() && !href.isEmpty()) {
             if (settings->logDnsPrefetchAndPreconnect())
                 document.addConsoleMessage(ConsoleMessage::create(OtherMessageSource, DebugMessageLevel, String("DNS prefetch triggered for " + href.host())));
-            networkHintsInterface.dnsPrefetchHost(href.host());
+            networkHintsInterface.dnsPrefetchHost(href);
         }
     }
 }
 
 static void preconnectIfNeeded(const LinkRelAttribute& relAttribute, const KURL& href, Document& document, const CrossOriginAttributeValue crossOrigin, const NetworkHintsInterface& networkHintsInterface, LinkCaller caller)
 {
     if (relAttribute.isPreconnect() && href.isValid() && href.protocolIsInHTTPFamily()) {
         UseCounter::count(document, UseCounter::LinkRelPreconnect);
         if (caller == LinkCalledFromHeader)
             UseCounter::count(document, UseCounter::LinkHeaderPreconnect);
@@ skipping 231 matching lines @@
 DEFINE_TRACE(LinkLoader)
 {
     visitor->trace(m_client);
     visitor->trace(m_prerender);
     visitor->trace(m_linkPreloadResourceClient);
     ResourceOwner<Resource, ResourceClient>::trace(visitor);
     PrerenderClient::trace(visitor);
 }
 
 } // namespace blink