Removes unused ADM APIs (final stage) BUG=webrtc:7306 Review-Url: https://codereview.webrtc.org/3006333003 Cr-Original-Commit-Position: refs/heads/master@{#19769} Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc Cr-Mirrored-Commit: e0406fd955239769c02a16f13e5739ae6b9d4bb8