468da7c074
This CL interfaces the SDP information (payload types and SSRCs) about FlexFEC with the corresponding configs at the Call layer. It also adds a field trial, which when active will expose FlexFEC in the default codec list, thus showing up in the default SDP. BUG=webrtc:5654 R=magjed@webrtc.org, stefan@webrtc.org CC=perkj@webrtc.org Review-Url: https://codereview.webrtc.org/2511703002 Cr-Commit-Position: refs/heads/master@{#15184}