Revert of AcmReceiver::DecoderByPayloadType: Ask NetEq for decoder (patchset #1 id:1 of https://codereview.webrtc.org/2341283002/ )

Reason for revert:
Seems to have broken Chromium tests.

Original issue's description:
> AcmReceiver::DecoderByPayloadType: Ask NetEq for decoder
>
> Instead of looking in AcmReceiver::decoders_, which we're trying to
> get rid of.
>
> BUG=webrtc:5801
>
> Committed: https://crrev.com/07772e4738ef8007280f97a0245eef34b9ca9391
> Cr-Commit-Position: refs/heads/master@{#14276}

TBR=ossu@webrtc.org,henrik.lundin@webrtc.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=webrtc:5801

Review-Url: https://codereview.webrtc.org/2346173002
Cr-Original-Commit-Position: refs/heads/master@{#14277}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: f62b82e95ffd720c454d668932f3694b9bd8e34b
2 files changed