Update AecDump API to match RtcEventLog API signature.

This will ease Swift interop.

NOTRY=True
BUG=

Review-Url: https://codereview.webrtc.org/2279293003
Cr-Original-Commit-Position: refs/heads/master@{#13978}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: fce0e2c2f6c2e16e73043af210b0fbb1641e0835
4 files changed