Revert 87415 - Convert more interfaces to the new thunk system. This goes up to and including

webkit/plugins/ppapi/resource_tracker.cc

Index: webkit/plugins/ppapi/resource_tracker.cc
===================================================================
--- webkit/plugins/ppapi/resource_tracker.cc	(revision 87436)
+++ webkit/plugins/ppapi/resource_tracker.cc	(working copy)
@@ -290,13 +290,6 @@
   return proxy.get();
 }
 
-PP_Instance ResourceTracker::GetInstanceForResource(PP_Resource pp_resource) {
-  scoped_refptr<Resource> resource(GetResource(pp_resource));
-  if (!resource.get())
-    return 0;
-  return resource->instance()->pp_instance();
-}
-
 scoped_refptr<Var> ResourceTracker::GetVar(int32 var_id) const {
   DLOG_IF(ERROR, !CheckIdType(var_id, PP_ID_TYPE_VAR))
       << var_id << " is not a PP_Var ID.";