Add field-initializing constructors to generated mojo structs.

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

Index: mojo/public/tools/bindings/generators/cpp_templates/wrapper_class_definition.tmpl
diff --git a/mojo/public/tools/bindings/generators/cpp_templates/wrapper_class_definition.tmpl b/mojo/public/tools/bindings/generators/cpp_templates/wrapper_class_definition.tmpl
index e6d04268520aa5f0f0a77a4c4e14839711d1c5ed..7f6c24d6549e16740fa67112bbc778a0ca1fa722 100644
--- a/mojo/public/tools/bindings/generators/cpp_templates/wrapper_class_definition.tmpl
+++ b/mojo/public/tools/bindings/generators/cpp_templates/wrapper_class_definition.tmpl
@@ -1,18 +1,23 @@
-// static
-{{struct.name}}Ptr {{struct.name}}::New() {
-  {{struct.name}}Ptr rv;
-  mojo::internal::StructHelper<{{struct.name}}>::Initialize(&rv);
-  return rv;
-}
-
-{{struct.name}}::{{struct.name}}()
-{%- for field in struct.fields %}
-    {% if loop.first %}:{% else %} {% endif %} {{field.name}}({{field|default_value}}){% if not loop.last %},{% endif %}
-{%- endfor %} {
-}
-
-{{struct.name}}::~{{struct.name}}() {
-}
+{% for num_params in range(struct|num_constructor_params) %}
+{{struct.name}}::{{struct.name}}(
+{%-  for field in struct.fields[:num_params]  %}
+{%-    set type = field.kind|cpp_wrapper_param_type %}
+{%-    set name = field.name %}
+    {{type}} {{name}}_in
+{%-    if not loop.last -%},{%- endif %}
+{%-  endfor %})
+{%-  for field in struct.fields %}
+{%-    set name = field.name %}
+    {% if loop.first %}:{% else %} {% endif %} {{name}}(
+{%-    if loop.index0 < num_params -%}
+std::move({{name}}_in)
+{%-    else -%}
+{{ field|default_value }}
+{%-    endif -%}
+){%  if not loop.last %},{% endif %}
+{%-  endfor %} {}
+{% endfor %}
+{{struct.name}}::~{{struct.name}}() = default;
 
 {%- if struct|is_hashable %}
 size_t {{struct.name}}::Hash(size_t seed) const {