Support private values in GN.

tools/gn/function_set_defaults.cc

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "tools/gn/err.h"
 #include "tools/gn/functions.h"
 #include "tools/gn/parse_tree.h"
 #include "tools/gn/scope.h"
 
 namespace functions {
@@ skipping 66 matching lines @@
 
   // Run the block for the rule invocation.
   Scope block_scope(scope);
   block->ExecuteBlockInScope(&block_scope, err);
   if (err->has_error())
     return Value();
 
   // Now copy the values set on the scope we made into the free-floating one
   // (with no containing scope) used to hold the target defaults.
   Scope* dest = scope->MakeTargetDefaults(target_type);
-  block_scope.NonRecursiveMergeTo(dest, false, function,
+  block_scope.NonRecursiveMergeTo(dest, Scope::MergeOptions(), function,
                                   "<SHOULD NOT FAIL>", err);
   return Value();
 }
 
 }  // namespace functions