Merge "Expose getTx/RxBytes in TrafficStats" am: 6ef6648cd9 am: aca01cd0c1 am: e0f68a4855

Original change: https://android-review.googlesource.com/c/platform/frameworks/base/+/1440245

Change-Id: I755eb6294da6cba787f60d057997a4d239aaa095