Mojo C++ Bindings: fix mojom::Foo::Deserialize() for component build.

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

 class {{export_attribute}} {{struct.name}} {
  public:
   using DataView = {{struct.name}}DataView;
   using Data_ = internal::{{struct.name}}_Data;
 
 {#--- Enums #}
 {%- for enum in struct.enums -%}
   using {{enum.name}} = {{enum|get_name_for_kind(flatten_nested_kind=True)}};
 {%- endfor %}
 
@@ skipping 55 matching lines @@
   static {{serialization_result_type}} Serialize(UserType* input) {
     return mojo::internal::StructSerializeImpl<
         {{struct.name}}::DataView, {{serialization_result_type}}>(input);
   }
 
   template <typename UserType>
   static bool Deserialize(const {{serialization_result_type}}& input,
                           UserType* output) {
     return mojo::internal::StructDeserializeImpl<
         {{struct.name}}::DataView, {{serialization_result_type}}>(
-            input, output);
+            input, output, Validate);
   }
 
 {#--- Struct members #}
 {%  for field in struct.fields %}
 {%-   set type = field.kind|cpp_wrapper_type %}
 {%-   set name = field.name %}
   {{type}} {{name}};
 {%- endfor %}
 
+ private:
+  static bool Validate(const void* data,
+                       mojo::internal::ValidationContext* validation_context);
+
 {%- if struct|contains_move_only_members %}
- private:
   DISALLOW_COPY_AND_ASSIGN({{struct.name}});
 {%- endif %}
 };