[mojo] Expose interface method min_versions

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

 {%- import "interface_macros.tmpl" as interface_macros %}
 class {{interface.name}}Proxy;
 
 template <typename ImplRefTraits>
 class {{interface.name}}Stub;
 
 class {{interface.name}}RequestValidator;
 {%- if interface|has_callbacks %}
 class {{interface.name}}ResponseValidator;
 {%- endif %}
@@ skipping 11 matching lines @@
   template <typename ImplRefTraits>
   using Stub_ = {{interface.name}}Stub<ImplRefTraits>;
 
   using RequestValidator_ = {{interface.name}}RequestValidator;
 {%- if interface|has_callbacks %}
   using ResponseValidator_ = {{interface.name}}ResponseValidator;
 {%- else %}
   using ResponseValidator_ = mojo::PassThroughFilter;
 {%- endif %}
 
+{#--- Metadata #}
+  enum kMethodIndices : uint32_t {

[yzshen1, 2016/12/22 18:53:28]

For Foo.Bar(), we already have "const uint32_t internal::kFoo_Bar_Name" defined.
Can we merge the two?

+{%- for method in interface.methods %}
+    k{{method.name}}MethodIndex,
+{%- endfor %}
+    kMethodMetadataSize
+  };
+
+  static const mojo::MethodMetadata kMethodMetadata[];
+
 {#--- Enums #}
 {%- for enum in interface.enums %}
   using {{enum.name}} = {{enum|get_name_for_kind(flatten_nested_kind=True)}};
 {%- endfor %}
 
 {#--- Constants #}
 {%- for constant in interface.constants %}
 {%-   if constant.kind|is_integral_kind %}
   static const {{constant.kind|cpp_pod_type}} {{constant.name}} = {{constant|constant_value}};
 {%-   else %}
@@ skipping 11 matching lines @@
   // should implement the signature with callback below.
   virtual bool {{method.name}}({{interface_macros.declare_sync_method_params("", method)}});
 {%-     endif %}
 
   using {{method.name}}Callback = {{interface_macros.declare_callback(method,
       for_blink, use_once_callback)}};
 {%-   endif %}
   virtual void {{method.name}}({{interface_macros.declare_request_params("", method, use_once_callback)}}) = 0;
 {%- endfor %}
 };