Reland of "Log audio network adapter decisions in event log."

This was originally reviewed https://codereview.webrtc.org/2559953002/

It was reverted due to a bug in the original CL, see https://codereview.webrtc.org/2631703002/

This CL is to fix and reland.

BUG=webrtc:6845

Review-Url: https://codereview.webrtc.org/2644863002
Cr-Original-Commit-Position: refs/heads/master@{#16242}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 4b7c952376bec4797307b106796c5612d930f206
21 files changed