Source

File: wp-admin/includes/template.php

function _media_states( $post ) {
	static $header_images;

	$media_states = array();
	$stylesheet   = get_option( 'stylesheet' );

	if ( current_theme_supports( 'custom-header' ) ) {
		$meta_header = get_post_meta( $post->ID, '_wp_attachment_is_custom_header', true );

		if ( is_random_header_image() ) {
			if ( ! isset( $header_images ) ) {
				$header_images = wp_list_pluck( get_uploaded_header_images(), 'attachment_id' );
			}

			if ( $meta_header === $stylesheet && in_array( $post->ID, $header_images, true ) ) {
				$media_states[] = __( 'Header Image' );
			}
		} else {
			$header_image = get_header_image();

			// Display "Header Image" if the image was ever used as a header image.
			if ( ! empty( $meta_header ) && $meta_header === $stylesheet && wp_get_attachment_url( $post->ID ) !== $header_image ) {
				$media_states[] = __( 'Header Image' );
			}

			// Display "Current Header Image" if the image is currently the header image.
			if ( $header_image && wp_get_attachment_url( $post->ID ) === $header_image ) {
				$media_states[] = __( 'Current Header Image' );
			}
		}
	}

	if ( current_theme_supports( 'custom-background' ) ) {
		$meta_background = get_post_meta( $post->ID, '_wp_attachment_is_custom_background', true );

		if ( ! empty( $meta_background ) && $meta_background === $stylesheet ) {
			$media_states[] = __( 'Background Image' );

			$background_image = get_background_image();
			if ( $background_image && wp_get_attachment_url( $post->ID ) === $background_image ) {
				$media_states[] = __( 'Current Background Image' );
			}
		}
	}

	if ( (int) get_option( 'site_icon' ) === $post->ID ) {
		$media_states[] = __( 'Site Icon' );
	}

	if ( (int) get_theme_mod( 'custom_logo' ) === $post->ID ) {
		$media_states[] = __( 'Logo' );
	}

	/**
	 * Filters the default media display states for items in the Media list table.
	 *
	 * @since 3.2.0
	 * @since 4.8.0 Added the `$post` parameter.
	 *
	 * @param string[] $media_states An array of media states. Default 'Header Image',
	 *                               'Background Image', 'Site Icon', 'Logo'.
	 * @param WP_Post  $post         The current attachment object.
	 */
	$media_states = apply_filters( 'display_media_states', $media_states, $post );

	if ( ! empty( $media_states ) ) {
		$state_count = count( $media_states );
		$i           = 0;

		echo ' — ';

		foreach ( $media_states as $state ) {
			$sep = ( ++$i === $state_count ) ? '' : ', ';

			echo "<span class='post-state'>$state$sep</span>";
		}
	}
}