[mojo-bindings] Support reuse of native enum classes

mojo/public/tools/bindings/generators/cpp_templates/module.h.tmpl

 // Copyright 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.
 
 {%- if variant -%}
 {%-   set variant_path = "%s-%s"|format(module.path, variant) -%}
 {%- else -%}
 {%-   set variant_path = module.path -%}
 {%- endif -%}
 
 {%- set header_guard = "%s_H_"|format(
         variant_path|upper|replace("/","_")|replace(".","_")|
             replace("-", "_")) %}
 
 #ifndef {{header_guard}}
 #define {{header_guard}}
 
 #include <stdint.h>
 #include <ostream>
 
 #include "mojo/public/cpp/bindings/array.h"
 #include "mojo/public/cpp/bindings/associated_interface_ptr.h"
 #include "mojo/public/cpp/bindings/associated_interface_ptr_info.h"
 #include "mojo/public/cpp/bindings/associated_interface_request.h"
 #include "mojo/public/cpp/bindings/callback.h"
+#include "mojo/public/cpp/bindings/enum_traits.h"
 #include "mojo/public/cpp/bindings/interface_ptr.h"
 #include "mojo/public/cpp/bindings/interface_request.h"
 #include "mojo/public/cpp/bindings/lib/control_message_handler.h"
 #include "mojo/public/cpp/bindings/lib/control_message_proxy.h"
 #include "mojo/public/cpp/bindings/lib/native_serialization.h"
 #include "mojo/public/cpp/bindings/map.h"
 #include "mojo/public/cpp/bindings/message_filter.h"
 #include "mojo/public/cpp/bindings/no_interface.h"
 #include "mojo/public/cpp/bindings/string.h"
 #include "mojo/public/cpp/bindings/struct_ptr.h"
@@ skipping 143 matching lines @@
 {%- endfor %}
 
 {%- if variant %}
 }  // namespace {{variant}}
 {%- endif %}
 {%- for namespace in namespaces_as_array|reverse %}
 }  // namespace {{namespace}}
 {%- endfor %}
 
 #endif  // {{header_guard}}