Don't start prerenders for prerendered pages queued for deletion.

chrome/browser/prerender/prerender_manager.cc

Index: chrome/browser/prerender/prerender_manager.cc
===================================================================
--- chrome/browser/prerender/prerender_manager.cc	(revision 184822)
+++ chrome/browser/prerender/prerender_manager.cc	(working copy)
@@ -271,6 +271,20 @@
             .GetDefaultSessionStorageNamespace();
   }
 
+  // If the prerender request comes from a recently cancelled prerender that
+  // |this| still owns, then abort the prerender.
+  for (ScopedVector<PrerenderData>::iterator it = to_delete_prerenders_.begin();
+       it != to_delete_prerenders_.end(); ++it) {
+    PrerenderContents* prerender_contents = (*it)->contents();
+    int contents_child_id;
+    int contents_route_id;
+    if (prerender_contents->GetChildId(&contents_child_id) &&
+        prerender_contents->GetRouteId(&contents_route_id) &&
+        contents_child_id == process_id && contents_route_id == route_id) {
+      return NULL;
+    }
+  }
+
   if (PrerenderData* parent_prerender_data =
           FindPrerenderDataForChildAndRoute(process_id, route_id)) {
     // Instead of prerendering from inside of a running prerender, we will defer