Remove the VoEDtmf interface.

webrtc/voice_engine/test/auto_test/fixtures/after_streaming_fixture.cc

 /*
  *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #include "webrtc/voice_engine/test/auto_test/fixtures/after_streaming_fixture.h"
+#include "webrtc/voice_engine/voice_engine_impl.h"
 
 AfterStreamingFixture::AfterStreamingFixture()
     : BeforeStreamingFixture() {
+  webrtc::VoiceEngineImpl* voe_impl =
+      static_cast<webrtc::VoiceEngineImpl*>(voice_engine_);
+  channel_proxy_ = voe_impl->GetChannelProxy(channel_);
   ResumePlaying();
 }