Extract the parameters for the encoder stack from the CodecManager

BUG=webrtc:5028

Review URL: https://codereview.webrtc.org/1459193002

Cr-Original-Commit-Position: refs/heads/master@{#10750}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 1379f1f1e69632485d07ac7a3a575ea231e62522
5 files changed