Enable history and downloads by default, port NewTabUI from DOMUIHost to DOMU...

chrome/browser/dom_ui/dom_ui.cc

Index: chrome/browser/dom_ui/dom_ui.cc
===================================================================
--- chrome/browser/dom_ui/dom_ui.cc	(revision 10343)
+++ chrome/browser/dom_ui/dom_ui.cc	(working copy)
@@ -79,6 +79,12 @@
   message_callbacks_.insert(std::make_pair(message, callback));
 }
 
+void DOMUI::RequestOpenURL(const GURL& url,
+                           const GURL& /* referer */,
+                           WindowOpenDisposition disposition) {
+  get_contents()->OpenURL(url, GURL(), disposition, PageTransition::LINK);
+}
+
 // DOMUI, protected: ----------------------------------------------------------
 
 void DOMUI::AddMessageHandler(DOMMessageHandler* handler) {