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

Review URL: https://codereview.webrtc.org/2061193002 .

Cr-Original-Commit-Position: refs/heads/master@{#13210}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: a7d88d38448f6a5677a017562765ab505b89d468
34 files changed