Note: this list is generated by looking for the string for this theme hook, so it may include some references that are not actually using this theme hook.

backdrop_common_theme in core/includes/
Provides theme registration for themes across .inc files.
backdrop_deliver_html_page in core/includes/
Packages and sends the result of a page callback to the browser as HTML.
template_preprocess_maintenance_page in core/includes/
Prepares variables for maintenance-page templates.
theme_install_page in core/includes/
Returns HTML for the installation page.
theme_update_page in core/includes/
Returns HTML for the update page.
_backdrop_log_error in core/includes/
Logs a PHP error or exception and displays an error page in fatal cases.
_batch_progress_page in core/includes/
Outputs a batch processing page.