Mojo: Expose untyped associated endpoints through public API

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

 {#  TODO(yzshen): Make these templates more readable. #}
 
 {#  Computes the serialized size for the specified struct.
     |struct| is the struct definition.
     |input_field_pattern| should be a pattern that contains one string
     placeholder, for example, "input->%s", "p_%s". The placeholder will be
     substituted with struct field names to refer to the input fields.
     |context| is the name of the serialization context.
     |input_may_be_temp| indicates whether any input may be temporary obejcts.
     We need to assign temporary objects to local variables before passing it to
@@ skipping 105 matching lines @@
       !{{output}}->{{name}}.is_valid(),
 {%-       endif %}
       mojo::internal::VALIDATION_ERROR_UNEXPECTED_INVALID_HANDLE,
       "invalid {{name}} in {{struct_display_name}}");
 {%-     endif %}
 {%-   elif kind|is_associated_kind %}
   // TODO(yzshen): add some DCHECKs for non-nullable, is_local, correct router, etc.
 {%-     if kind|is_associated_interface_kind %}
   mojo::internal::AssociatedInterfacePtrInfoToData(std::move({{input_field}}), &{{output}}->{{name}});
 {%-     else %}
-  {{output}}->{{name}} = mojo::internal::AssociatedInterfaceRequestHelper::PassHandle(&{{input_field}}).release();
+  {{output}}->{{name}} = {{input_field}}.PassHandle().release();
 {%-     endif %}
 {%-   elif kind|is_enum_kind %}
   {{output}}->{{name}} = static_cast<int32_t>({{input_field}});
 {%-   else %}
   {{output}}->{{name}} = {{input_field}};
 {%-   endif %}
 {%- endfor %}
 {%- endmacro -%}
 
 {#  Deserializes the specified struct.
@@ skipping 19 matching lines @@
   if (!{{input}}.Read{{name|under_to_camel}}(&{{output_field}}))
     {{success}} = false;
 {%-     elif kind|is_interface_kind or kind|is_any_handle_kind or
              kind|is_associated_kind %}
   {{output_field}} = {{input}}.Take{{name|under_to_camel}}();
 {%-     else %}
   {{output_field}} = {{input}}.{{name}}();
 {%-     endif %}
 {%-   endfor %}
 {%- endmacro %}