Safely cancel prerenders on threads other than the UI thread

content/browser/renderer_host/resource_dispatcher_host.h

Index: content/browser/renderer_host/resource_dispatcher_host.h
===================================================================
--- content/browser/renderer_host/resource_dispatcher_host.h	(revision 86075)
+++ content/browser/renderer_host/resource_dispatcher_host.h	(working copy)
@@ -244,14 +244,6 @@
   static bool is_prefetch_enabled();
   static void set_is_prefetch_enabled(bool value);
 
-  void AddPrerenderChildRoutePair(int child_id, int route_id);
-  void RemovePrerenderChildRoutePair(int child_id, int route_id);
-
-  typedef std::set<std::pair<int, int> > PrerenderChildRouteIdPairs;
-  const PrerenderChildRouteIdPairs& prerender_child_route_id_pairs() const {
-    return prerender_child_route_pairs_;
-  }
-
  private:
   FRIEND_TEST_ALL_PREFIXES(ResourceDispatcherHostTest,
                            TestBlockedRequestsProcessDies);
@@ -384,8 +376,6 @@
                         const GURL& new_first_party_for_cookies);
   void OnReleaseDownloadedFile(int request_id);
 
-  bool IsPrerenderingChildRoutePair(int child_id, int route_id) const;
-
   ResourceHandler* CreateSafeBrowsingResourceHandler(
       ResourceHandler* handler, int child_id, int route_id,
       ResourceType::Type resource_type);
@@ -487,7 +477,6 @@
   ResourceMessageFilter* filter_;
 
   static bool is_prefetch_enabled_;
-  PrerenderChildRouteIdPairs prerender_child_route_pairs_;
 
 
   DISALLOW_COPY_AND_ASSIGN(ResourceDispatcherHost);