Implement Wifi scan Westworld logging.

Bug: 171790175
Test: atest WifiMetricsTest, also manual

>  make statsd_testdrive
>  ./out/host/linux-x86/bin/statsd_testdrive 320320
Open settings on device, observe scan atoms in the log.

Change-Id: Iaf015e86dd76b8c2f762bfc8f58d0881c9b2a7cb
6 files changed
tree: 31669f08172a0dd7a4d1c7ad10ecd260e75b5e74
  1. apex/
  2. service/
  3. metrics_pdd_hook.py
  4. PREUPLOAD.cfg