Revert 284958 "Make HistoryDBTask not refcounted, and ensure it'..."

trunk/src/chrome/browser/prerender/prerender_local_predictor.cc

Index: trunk/src/chrome/browser/prerender/prerender_local_predictor.cc
===================================================================
--- trunk/src/chrome/browser/prerender/prerender_local_predictor.cc	(revision 285001)
+++ trunk/src/chrome/browser/prerender/prerender_local_predictor.cc	(working copy)
@@ -555,12 +555,10 @@
     RecordEvent(EVENT_GOT_HISTORY_ISSUING_LOOKUP);
     CandidatePrerenderInfo* lookup_info_ptr = lookup_info.get();
     history->ScheduleDBTask(
-        scoped_ptr<history::HistoryDBTask>(
-            new GetURLForURLIDTask(
-                lookup_info_ptr,
-                base::Bind(&PrerenderLocalPredictor::OnLookupURL,
-                           base::Unretained(this),
-                           base::Passed(&lookup_info)))),
+        new GetURLForURLIDTask(lookup_info_ptr,
+                               base::Bind(&PrerenderLocalPredictor::OnLookupURL,
+                                          base::Unretained(this),
+                                          base::Passed(&lookup_info))),
         &history_db_tracker_);
   }
 }
@@ -1000,10 +998,8 @@
   HistoryService* history = GetHistoryIfExists();
   if (history) {
     CHECK(!is_visit_database_observer_);
-    history->ScheduleDBTask(
-        scoped_ptr<history::HistoryDBTask>(
-            new GetVisitHistoryTask(this, kMaxVisitHistory)),
-        &history_db_tracker_);
+    history->ScheduleDBTask(new GetVisitHistoryTask(this, kMaxVisitHistory),
+                            &history_db_tracker_);
     history->AddVisitDatabaseObserver(this);
     is_visit_database_observer_ = true;
   } else {