[automerger skipped] [SP18.4] Add unit test for polling network stats in OffloadController am: 3f1c755662 am: 265433ba19 -s ours

am skip reason: Change-Id I9b9c9c096a2366aaf383d5c2d567db6682f02dad with SHA-1 3f1c755662 is in history

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/11367681

Change-Id: I178d6566b7b1783b212f44aa1ce6db8868127af0