How can I set custom bounds for my custom map?

Below is example to set a map.

<div id="googleMap" style="height:400px;width:100%;"></div>

<!-- Add Google Maps -->
<script src="https://maps.googleapis.com/maps/api/js"></script>
<script>
    var myCenter = new google.maps.LatLng(22.7541475, 75.8972077);

    function initialize() {
        var mapProp = {
            center: myCenter,
            zoom: 12,
            scrollwheel: false,
            draggable: false,
            mapTypeId: google.maps.MapTypeId.ROADMAP
        };

        var map = new google.maps.Map(document.getElementById("googleMap"), mapProp);

        var marker = new google.maps.Marker({
            position: myCenter,
        });

        marker.setMap(map);
    }

    google.maps.event.addDomListener(window, 'load', initialize);
</script>

For Leaflet bounds..

var group = new L.featureGroup([marker1, marker2, marker3]);
map.fitBounds(group.getBounds());

See here for more info.