Remove deprecated CodecType methods.

These are no longer needed as all clients have been updated to use the
new methods that always return a value.

BUG=None

Review-Url: https://codereview.webrtc.org/3009583002
Cr-Original-Commit-Position: refs/heads/master@{#19559}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 1a92d0de49779567241e97e50cb69d51257adcce
2 files changed