WordPress at a glance
filter is not described

wp_cache_ob_callback_filter filter-hook . WPSCache 1.0

Usage

add_filter( 'wp_cache_ob_callback_filter', 'filter_function_name_2471' );
function filter_function_name_2471( $buffer ){
	// filter...

	return $buffer;
}
$buffer
-

Where the hook is called

wp_cache_ob_callback()
wp_cache_ob_callback_filter
wp-super-cache/wp-cache-phase2.php 1797
$buffer = apply_filters( 'wp_cache_ob_callback_filter', $buffer );

Where in WP core the hook is used WP Super Cache

wp-super-cache/ossdl-cdn.php 227
add_filter( 'wp_cache_ob_callback_filter', 'scossdl_off_filter' );