The comment passed validation and is about to be saved.
Modules may make changes to the comment before it is saved to the database.
$comment: The comment object.
Note: this list is generated by pattern matching, so it may include some functions that are not actually implementations of this hook.
function hook_comment_presave($comment) {
// Remove leading & trailing spaces from the comment subject.
$comment->subject = trim($comment->subject);
}