google/data-layer-helper — pull request #3 by AlexRNau (2014-02-03 18:34:51+00:00)
Title: Added support for Command Arrays and Custom Methods, which should allow users to easily modify data in the dataLayer.

This matches as close as possible to the code you've seen before. The only difference is the interface is local to the processUpdates_ method instead of being a member variable to the class. I couldn't seem to get it to work out but maybe you'll see what I was missing.