WP_Customize_Background_Position_Control
Customize Background Position Control class.
WordPress File wp-includes/customize/class-wp-customize-background-position-control.php
WP_Customize_Background_Position_Control::content_template()
Render a JS template for the content of the position control.
WP_Customize_Background_Position_Control::render_content()
Don’t render the control content from PHP, as it’s rendered via JS on load.