placeholder_builder.Attr(outside_compilation_attr_name,
                               outside_compilation_attr);
      placeholder_builder.Attr(kOutsideCompilationOriginalNodeAttrName,
                               src->name());
      placeholder_builder.Attr(kOutsideCompilationSrcOutputAttrName,
                               src_output);
      NodeDef placeholder_def;

// Attribute indicating that this is an Placeholder node added to act as a
// temporary input node for an outside compilation node. Attribute value will be
// string (original input node name).
extern const char kOutsideCompilationOriginalNodeAttrName[];

// Attribute indicating that this is an Placeholder node added to act as a
// temporary input node for an outside compilation node. Attribute value will be
// int (src_output for original edge).