Reland of move audio/video distinction for probe packets. (patchset #1 id:1 of https://codereview.webrtc.org/2086633002/ )

Reason for revert:
Fix already landed in google3, this revert actually breaks the import.

Original issue's description:
> Revert of Remove audio/video distinction for probe packets. (patchset #2 id:20001 of https://codereview.webrtc.org/2061193002/ )
>
> Reason for revert:
> Revert this because it broke the google3 import build.
> http://webrtc-buildbot-master.mtv.corp.google.com:21000/builders/WebRTC%20google3%20Importer%20%28Shem%20TOT%29/builds/67/steps/blaze_regular_tests/logs/stdio
>
> Original issue's description:
> > Remove audio/video distinction for probe packets.
> >
> > Allows detecting large-enough audio packets as part of a probe,
> > speculative fix for a rampup-time regression in M50. These packets are
> > accounted on the send side when probing.
> >
> > BUG=webrtc:5985
> > R=mflodman@webrtc.org, philipel@webrtc.org
> >
> > Committed: https://crrev.com/a7d88d38448f6a5677a017562765ab505b89d468
> > Cr-Commit-Position: refs/heads/master@{#13210}
>
> TBR=mflodman@webrtc.org,philipel@webrtc.org,pbos@webrtc.org
> # Skipping CQ checks because original CL landed less than 1 days ago.
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=webrtc:5985
>
> Committed: https://crrev.com/17bde8c96ee8b5a7e496a7dc98828b84f9756925
> Cr-Commit-Position: refs/heads/master@{#13221}

TBR=mflodman@webrtc.org,philipel@webrtc.org,honghaiz@webrtc.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=webrtc:5985

Review-Url: https://codereview.webrtc.org/2085653002
Cr-Original-Commit-Position: refs/heads/master@{#13223}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 2169d8bc68ac9ae8aa0795bf2f37586aa87f8878
34 files changed