Convert Pass()→std::move() in generated Mojo bindings.

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

 // static
 {{union.name}}Ptr {{union.name}}::New() {
   {{union.name}}Ptr rv;
   mojo::internal::StructHelper<{{union.name}}>::Initialize(&rv);
-  return rv.Pass();
+  return rv;
 }
 
 {{union.name}}::{{union.name}}() {
   // TODO(azani): Implement default values here when/if we support them.
   // TODO(azani): Set to UNKNOWN when unknown is implemented.
   SetActive(static_cast<Tag>(0));
 }
 
 {{union.name}}::~{{union.name}}() {
   DestroyActive();
 }
 
 {%  if union|is_cloneable_kind %}
 {{union.name}}Ptr {{union.name}}::Clone() const {
   {{union.name}}Ptr rv(New());
   switch (tag_) {
 {%    for field in union.fields %}
     case Tag::{{field.name|upper}}:
 {%    if field.kind|is_string_kind %}
       rv->set_{{field.name}}(*(data_.{{field.name}}));
 {%    elif field.kind|is_object_kind %}
       rv->set_{{field.name}}(data_.{{field.name}}->Clone());
 {%-   else %}
       rv->set_{{field.name}}(data_.{{field.name}});
 {%-   endif %}
       break;
 {%-   endfor %}
   };
-  return rv.Pass();
+  return rv;
 }
 {%- endif %}
 
 bool {{union.name}}::Equals(const {{union.name}}& other) const {
   if (tag_ != other.which()) {
     return false;
   }
 
   switch (tag_) {
 {%  for field in union.fields %}
@@ skipping 24 matching lines @@
   return data_.{{field.name}};
 {%-   endif %}
 }
 
 void {{union.name}}::set_{{field.name}}({{field.kind|cpp_const_wrapper_type}} {{field.name}}) {
   SwitchActive(Tag::{{field.name|upper}});
 {%    if field.kind|is_string_kind %}
   *(data_.{{field.name}}) = {{field.name}};
 {%    elif field.kind|is_object_kind or field.kind|is_interface_kind or
            field.kind|is_associated_kind %}
-  *(data_.{{field.name}}) = {{field.name}}.Pass();
+  *(data_.{{field.name}}) = std::move({{field.name}});
 {%    elif field.kind|is_any_handle_kind %}
   data_.{{field.name}}->reset({{field.name}}.release());
 {%-   else %}
   data_.{{field.name}} = {{field.name}};
 {%-   endif %}
 }
 {%- endfor %}
 
 void {{union.name}}::SwitchActive(Tag new_active) {
   if (new_active == tag_) {
@@ skipping 24 matching lines @@
 {%  for field in union.fields %}
     case Tag::{{field.name|upper}}:
 {%    if field.kind|is_object_kind or field.kind|is_any_handle_kind or
          field.kind|is_interface_kind or field.kind|is_associated_kind %}
       delete data_.{{field.name}};
 {%-   endif %}
       break;
 {%- endfor %}
   }
 }