Remove PrerenderManager.enabled_ and related members.

chrome/browser/profiles/profile_impl.cc

Index: chrome/browser/profiles/profile_impl.cc
diff --git a/chrome/browser/profiles/profile_impl.cc b/chrome/browser/profiles/profile_impl.cc
index ccbc3cbb5d951db758b7bed07dfc0a9c9ea42d2a..9cfe5359a26af2cbf1c6b47bb0931650131c5988 100644
--- a/chrome/browser/profiles/profile_impl.cc
+++ b/chrome/browser/profiles/profile_impl.cc
@@ -984,10 +984,7 @@ void ProfileImpl::OnPrefsLoaded(bool success) {
   DCHECK(!net_pref_observer_);
   {
     TRACE_EVENT0("browser", "ProfileImpl::OnPrefsLoaded:NetPrefObserver")
-    net_pref_observer_.reset(new NetPrefObserver(
-        prefs_.get(),
-        prerender::PrerenderManagerFactory::GetForProfile(this),
-        predictor_));
+    net_pref_observer_.reset(new NetPrefObserver(prefs_.get()));
   }
 
   chrome_prefs::SchedulePrefsFilePathVerification(path_);