am 0369cf98: Cherry pick from Honeycomb Change ID I8d57d12828afab700d76f9b19195817a0adfe080 IAB docs: adds best practices for pending transaction UI

* commit '0369cf98743e72d052eb5542125f58d1ad2f7f61':
  Cherry pick from Honeycomb Change ID I8d57d12828afab700d76f9b19195817a0adfe080 IAB docs: adds best practices for pending transaction UI