demo-module.js

angular.module('demo', [])
  .provider('googleMaps', require('./google-maps-service-provider'))
  .config(['googleMapsProvider', function(googleMapsProvider) {
    googleMapsProvider.configure({
      key: 'your api key',
      language: 'de',
      libraries: 'places'
    });
  }])
  .controller('MapController', ['googleMaps', function(googleMaps) {
    googleMaps.then(function(googleMaps) {
      // now we can extend google-maps-classes
      function MarkerLabel_() {
      }
      inherits(MarkerLabel_, googleMaps.OverlayView);
    });
  }])
;

function inherits(childCtor, parentCtor) {
  /** @constructor */
  function tempCtor() {}
  tempCtor.prototype = parentCtor.prototype;
  childCtor.superClass_ = parentCtor.prototype;
  childCtor.prototype = new tempCtor();
  /** @override */
  childCtor.prototype.constructor = childCtor;
}

google-maps-service-provider.js

module.exports = [GoolgMapsServiceProvider];

function GoolgMapsServiceProvider() {
  
  // Some nice default options
  this.options = {
//    key: 'api-key here',
    v: '3.15',
    libraries: 'places',
    language: 'en',
    sensor: 'false'
  };
  
  // A function that lets us configure options of the service
  this.configure = function(options) {
    angular.extend(this.options, options);
  };
  
  // Return an instance of the service
  this.$get = ['$q', function($q) {
    return new GoolgMapsService($q, this.options);
  }];
}

// The service, that is a promise for a reference to window.google.maps
function GoolgMapsService($q, options) {
  var deferred = $q.defer();
  
  // Early-resolve if google-maps-api is already in global-scope
  if(typeof window.google !== 'undefined' && typeof window.google.maps !== 'undefined') {
    deferred.resolve(window.google.maps);
    return deferred.promise;
  }
  
  var randomizedFunctionName = options.callback = 'onGoogleMapsReady' + Math.round(Math.random()*1000);
  window[randomizedFunctionName] = function() {
    window[randomizedFunctionName] = null;
    // Resolve the promise
    deferred.resolve(window.google.maps);
  };
  
  var q = [];
  angular.forEach(options, function(v, k) {
    q.push(k+'='+v);
  });
  q = q.join('&');
  
  var script = document.createElement('script');
  script.type = 'text/javascript';
  script.src = 'https://maps.googleapis.com/maps/api/js?' + q;
  document.body.appendChild(script);
  
  // Return the promise
  return deferred.promise;
}

attempting to use this, it is not working.. any help is useful and appreciated

https://github.com/nlaplante/angular-google-maps/tree/master_maps_loader