[CC01] Remove the confusing pollForNextCallback

In Java, "poll" methods return null when the collection is
empty. Respect this convention.

Bug: 157405399
Test: FrameworksNetTests
Change-Id: I3b17908f9ce1f60b18908605a645da3199c010b9
2 files changed
tree: eb6a4d4993c113e180f511b6dc5ad1209d74581f
  1. staticlibs/