If you’re working on a mobile application using Cordova 4.0 + and you’re using Google Maps do not forget to install Cordova Whitelist plugin. As of Cordova 4.0 all external resources permissions can be done only through this plugin, which includesGoogle Maps.
I wrote an article on this topic, you will also find a working example there: Using Cordova Geoloacation API with Google Maps in Ionic Framework