Reason for revert: Breaks Chromium FYI bots for Android. E.g. https://build.chromium.org/p/chromium.webrtc.fyi/builders/Android%20Tests%20%28dbg%29%20%28K%20Nexus5%29/builds/4486/steps/content_browsertests/logs/stdio Original issue's description: > - Clean up unused voice engine DTMF code following removal of VoEDtmf APIs. > - Use better types in AudioSendStream::SendTelephoneEvent() and related methods. > > BUG=webrtc:4690 > > Committed: https://crrev.com/8886c816582a7c6190c5429222cb8096fca302a6 > Cr-Commit-Position: refs/heads/master@{#11927} TBR=tina.legrand@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:4690 Review URL: https://codereview.webrtc.org/1776243003 Cr-Commit-Position: refs/heads/master@{#11930}