Add support for rel=next to Prerender in Blink.

Source/core/loader/LinkLoader.cpp

Index: Source/core/loader/LinkLoader.cpp
diff --git a/Source/core/loader/LinkLoader.cpp b/Source/core/loader/LinkLoader.cpp
index 8517a62cfd7317e91e39c4ab83a5f08b72ce5e10..adbc51ea2ef82865a5e9ef0fbc4168ae271d940d 100644
--- a/Source/core/loader/LinkLoader.cpp
+++ b/Source/core/loader/LinkLoader.cpp
@@ -36,13 +36,25 @@
 #include "core/dom/Document.h"
 #include "core/fetch/FetchRequest.h"
 #include "core/fetch/ResourceFetcher.h"
+#include "core/frame/Settings.h"
 #include "core/html/LinkRelAttribute.h"
 #include "core/loader/PrerenderHandle.h"
-#include "core/frame/Settings.h"
+#include "platform/Prerender.h"
 #include "platform/network/DNS.h"
 
 namespace WebCore {
 
+static unsigned prerenderRelTypesFromRelAttribute(const LinkRelAttribute& relAttribute)
+{
+    unsigned result = 0;
+    if (relAttribute.isLinkPrerender())
+        result |= PrerenderRelTypePrerender;
+    if (relAttribute.isLinkNext())
+        result |= PrerenderRelTypeNext;
+
+    return result;
+}
+
 LinkLoader::LinkLoader(LinkLoaderClient* client)
     : m_client(client)
     , m_linkLoadTimer(this, &LinkLoader::linkLoadTimerFired)
@@ -119,13 +131,14 @@ bool LinkLoader::loadLink(const LinkRelAttribute& relAttribute, const AtomicStri
         setResource(document.fetcher()->fetchLinkResource(type, linkRequest));
     }
 
-    if (relAttribute.isLinkPrerender()) {
+    if (const unsigned prerenderRelTypes = prerenderRelTypesFromRelAttribute(relAttribute)) {
         if (!m_prerender) {
-            m_prerender = PrerenderHandle::create(document, this, href);
+            m_prerender = PrerenderHandle::create(document, this, href, prerenderRelTypes);
         } else if (m_prerender->url() != href) {
             m_prerender->cancel();
-            m_prerender = PrerenderHandle::create(document, this, href);
+            m_prerender = PrerenderHandle::create(document, this, href, prerenderRelTypes);
         }
+        // TODO(gavinp): Handle changes to rel types of existing prerenders.
     } else if (m_prerender) {
         m_prerender->cancel();
         m_prerender.clear();