Lazy load google maps before constructing class in angular factory - angularjs

Question

I have a module that uses google maps to make a map, get the users location and place a marker on the map where they are. I wanted a custom animated marker so I had to make a factory initializing a custom OverlayView Class. I also wanted the map loaded asynchronously so I created a factory like this
to handle loading google maps.
I can load the map fine by doing this:
initializer.gMapReady.then(function(){
//call service method to make map
});
But I dont know how to use my initializer for my OverlayView factory that looks like this:
.factory('locMarker', function() {
LocationMarker.prototype = new google.maps.OverlayView(); // This returns the error, google is not defined
function LocationMarker(opts) {
this.setValues(opts);
}
LocationMarker.prototype.draw = function() {
//
// Code for drawing the marker on the map
//
}
};
return LocationMarker;
})
Whenever I load the page the map shows up fine but my custom marker never displays. I get a reference error, google is not defined, that points to the line LocationMarker.prototype = new google.maps.OverlayView(); If I don't lazy load google maps and just add the script to the index page everything runs fine.
Is there a way for me to call my maps initializer from within the locMarker factory so that google maps is loaded before it tries to construct the class?
Update:
As estus mentioned in the comments, I could use a resolver in the states/routes but I am trying to make this module not require that if possible.