messaging.onBackgroundMessage is not getting called in web

Question

I have implemented FCM in push i want to redirect to my screen on click of push notification when app is in background. It is redirecting to my webpage but messaging.onBackgroundMessage is not getting called. This is my payload:

        $fields['notification'] = array();
        $fields['notification']['body'] = $message;
        $fields['notification']['title'] = $title;
        $fields['notification']['click_action'] = 'www.google.com';