Google api to fetch the location history of a user

As far as I'm aware there is no API that achieves what you're after. I don't even think the latitude API provided tracking for other users.

Logically it could be a bit of an invasion of privacy if it did exist. Most people don't read the T&C's or permissions when they install an app and it would be fairly easy to use this for the wrong purposes.

Although there is no API ready for use one can build together a script based on Curl that sets the right cookies and retrieves the content like described by Terence Eden [LINK].

Another way - although not well suited for an app - is to create an archive of your Google account information (select only location history information to keep it small) and therewith getting a Json-file with all location information.