Implement WebPrescientNetworking::prefetchDNS.

chrome/renderer/net/prescient_networking_dispatcher.cc

 // Copyright 2013 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.
 
 #include "chrome/renderer/net/prescient_networking_dispatcher.h"
 
+#include "base/strings/utf_string_conversions.h"
 #include "chrome/common/render_messages.h"
 #include "content/public/renderer/render_thread.h"
 
 using WebKit::WebPrescientNetworking;
 
 PrescientNetworkingDispatcher::~PrescientNetworkingDispatcher() {
 }
 
+void PrescientNetworkingDispatcher::prefetchDNS(
+    const WebKit::WebString& hostname) {
+  if (hostname.isEmpty())
+    return;
+
+  std::string hostname_utf8;
+  UTF16ToUTF8(hostname.data(), hostname.length(), &hostname_utf8);
+  net_predictor_.Resolve(hostname_utf8.data(), hostname_utf8.length());
+}
+
 void PrescientNetworkingDispatcher::preconnect(
     const WebKit::WebURL& url,
     WebKit::WebPreconnectMotivation motivation) {
   // FIXME(kouhei) actual pre-connecting is currently disabled.
   // This should shortly be enabled via Finch field trials in upcoming patch.
   // content::RenderThread::Get()->Send(new ChromeViewHostMsg_Preconnect(url));
 }