Design of Google Play Services

wanted to understand more about the design of google play services.

like to use it we need to create an object of GoogleApiClient(see below code) and then we need to add API to which we are interested.

GoogleApiClient mGoogleApiClient = new GoogleApiClient.Builder(this)
.enableAutoManage(this /* FragmentActivity */,
                  this /* OnConnectionFailedListener */)
.addApi(Drive.API)
.addScope(Drive.SCOPE_FILE)
.build();

can any body help me how they built it this whole mechanism. this article is help full http://ift.tt/299d44z but i want to understand more details.