If you put that URL directly into your browser you'll see that Google no longer allows you to do this without an API key:
http://maps.googleapis.com/maps/api/geocode/json?latlng=37.422290,-122.084057&sensor=true
Get an API key:
https://developers.google.com/maps/documentation/javascript/get-api-key
I think you can get a couple hundred dollars worth of api calls a month before you start getting charged. In the past I've used Bing Maps because it was still free to geocode (and I think still is):
Grab a key:
Geocode:
Maybe somebody has a better solution for something else to use nowadays.