For c++, Generate enum classes instead of enum from mojom.

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.
 
 {%- set header_guard = "%s_H_"|
         format(module.path|upper|replace("/","_")|replace(".","_")) %}
 
 #ifndef {{header_guard}}
 #define {{header_guard}}
 
 #include <stdint.h>
+#include <type_traits>
 
 #include "mojo/public/cpp/bindings/array.h"
 #include "mojo/public/cpp/bindings/callback.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/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"
 #include "{{module.path}}-internal.h"
 {%- for import in imports %}
 #include "{{import.module.path}}.h"
 {%- endfor %}
 
 {%- for namespace in namespaces_as_array %}
 namespace {{namespace}} {
 {%- endfor %}
 
 {#--- Enums #}
 {% from "enum_macros.tmpl" import enum_decl -%}
+{% from "enum_macros.tmpl" import global_enum_operators_decl -%}
 {%  for enum in enums %}
   {{enum_decl(enum)}}
+  {{global_enum_operators_decl(enum)}}
 {%- endfor %}
 
 {#--- Constants #}
 {%- for constant in module.constants %}
 {#-   To be consistent with constants defined inside interfaces, only make
       integral types compile-time constants. #}
 {%-   if constant.kind|is_integral_kind %}
 const {{constant.kind|cpp_pod_type}} {{constant.name}} = {{constant|constant_value}};
 {%-   else %}
 extern const {{constant.kind|cpp_pod_type}} {{constant.name}};
@@ skipping 86 matching lines @@
 {%    for union in unions %}
 {%      include "union_serialization_declaration.tmpl" %}
 {%-   endfor %}
 {%- endif %}
 
 {%- for namespace in namespaces_as_array|reverse %}
 }  // namespace {{namespace}}
 {%- endfor %}
 
 #endif  // {{header_guard}}