This event is fired when you tap on the location button.
<div id="map_canvas"></div>
var div = document.getElementById("map_canvas");
var map = plugin.google.maps.Map.getMap(div, {
controls: {
myLocationButton: true
}
});
map.one(plugin.google.maps.event.MAP_READY, function() {
map.on(plugin.google.maps.event.MY_LOCATION_BUTTON_CLICK, function() {
alert("The my location button is clicked.");
});
});