provato come dici tu vengo reindirizzato sulla pagina:

myphpfile.php?name=undefined

ti posto il codice modificato:




codice:
<!DOCTYPE html>
<html>
  <head>
    <title>Google Maps JavaScript API v3 Example: Map Geolocation</title>
    <meta name="viewport" content="initial-scale=1.0, user-scalable=no">
    <meta charset="utf-8">
    <link href="defaults.css" rel="stylesheet">
    <!--
    Include the maps javascript with sensor=true because this code is using a
    sensor (a GPS locator) to determine the user's location.
    See: https://developers.google.com/apis/m...ecifyingSensor
    -->
    <script src="https://maps.googleapis.com/maps/api/js?v=3.exp&sensor=true"></script>

    <script>
       var map;
var pos;
      function initialize() {
        var mapOptions = {
          zoom: 6,
          mapTypeId: google.maps.MapTypeId.ROADMAP
        };
        map = new google.maps.Map(document.getElementById('map_canvas'),
            mapOptions);

        // Try HTML5 geolocation
        if(navigator.geolocation) {
          navigator.geolocation.getCurrentPosition(function(position) {
    pos   = new google.maps.LatLng(position.coords.latitude,
                                             position.coords.longitude);

            var infowindow = new google.maps.InfoWindow({
              map: map,
              position: pos,
              content: 'Posizione Rilevata Tramite IP.'
			  
            });

            map.setCenter(pos);
          }, function() {
            handleNoGeolocation(true);
          });
        } else {
          // Browser doesn't support Geolocation
          handleNoGeolocation(false);
        }
      }

      function handleNoGeolocation(errorFlag) {
        if (errorFlag) {
          var content = 'Error: The Geolocation service failed.';
        } else {
          var content = 'Error: Your browser doesn\'t support geolocation.';
        }

        var options = {
          map: map,
          position: new google.maps.LatLng(60, 105),
          content: content
        };

        var infowindow = new google.maps.InfoWindow(options);
        map.setCenter(options.position);
      }
window.location.href = "myphpfile.php?name=" + pos;
      google.maps.event.addDomListener(window, 'load', initialize);
	  
    </script>
  </head>
  <body>
    <div id="map_canvas"></div>
  </body>
</html>