Remove unused method OutputMixer::PlayDtmfTone() and infrastructure.

webrtc/voice_engine/include/voe_errors.h

 /*
  *  Copyright (c) 2011 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.
  */
 
@@ skipping 29 matching lines @@
 #define VE_NOT_INITED 8026
 #define VE_NOT_SENDING 8027
 #define VE_EXT_TRANSPORT_NOT_SUPPORTED 8028
 #define VE_EXTERNAL_TRANSPORT_ENABLED 8029
 #define VE_STOP_RECORDING_FAILED 8030
 #define VE_INVALID_RATE 8031
 #define VE_INVALID_PACKET 8032
 #define VE_NO_GQOS 8033
 #define VE_INVALID_TIMESTAMP 8034
 #define VE_RECEIVE_PACKET_TIMEOUT 8035
-#define VE_STILL_PLAYING_PREV_DTMF 8036
+// 8036 is not used
 #define VE_INIT_FAILED_WRONG_EXPIRY 8037
 #define VE_SENDING 8038
 #define VE_ENABLE_IPV6_FAILED 8039
 #define VE_FUNC_NO_STEREO 8040
 // Range 8041-8080 is not used
 #define VE_FW_TRAVERSAL_ALREADY_INITIALIZED 8081
 #define VE_PACKET_RECEIPT_RESTARTED 8082
 #define VE_NOT_ALL_INFO 8083
 #define VE_CANNOT_SET_SEND_CODEC 8084
 #define VE_CODEC_ERROR 8085
@@ skipping 96 matching lines @@
 #define VE_CANNOT_STOP_PLAYOUT 10031
 #define VE_CANNOT_INIT_CHANNEL 10032
 #define VE_RECV_SOCKET_ERROR 10033
 #define VE_SOCKET_TRANSPORT_MODULE_ERROR 10034
 #define VE_AUDIO_CONF_MIX_MODULE_ERROR 10035
 
 // Warnings for other platforms (reserved range 8061-8080)
 #define VE_IGNORED_FUNCTION 8061
 
 #endif  //  WEBRTC_VOICE_ENGINE_VOE_ERRORS_H