Make the fuchsia mojo/public repo the source of truth.

mojo/public/tools/bindings/generators/cpp_templates/interface_declaration.tmpl

-{%- import "interface_macros.tmpl" as interface_macros %}
-class {{interface.name}}Proxy;
-class {{interface.name}}Stub;
-class {{interface.name}}_Synchronous;
-
-class {{interface.name}}RequestValidator;
-{%- if interface|has_callbacks %}
-class {{interface.name}}ResponseValidator;
-{%- endif %}
-
-class {{interface.name}} : public internal::{{interface.name}}_Base {
- public:
-  virtual ~{{interface.name}}() override {}
-
-  using Proxy_ = {{interface.name}}Proxy;
-  using Stub_ = {{interface.name}}Stub;
-
-{%- for method in interface.methods %}
-{%-    if method.response_parameters != None %}
-  using {{method.name}}Callback = {{interface_macros.declare_callback(method)}};
-{%-   endif %}
-  virtual void {{method.name}}({{interface_macros.declare_request_params("", method)}}) = 0;
-{%- endfor %}
-};