wp-includes/class-wp-customize-manager.php:4620Gets the initial URL to be previewed.
string public function get_preview_url() { if ( empty( $this->preview_url ) ) { $preview_url = home_url( '/' ); } else { $preview_url = $this->preview_url; } return $preview_url; }Introduced in 4.4.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/class-wp-customize-manager.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.