Revert of - Clean up unused voice engine DTMF code.

webrtc/voice_engine/transmit_mixer.cc

Index: webrtc/voice_engine/transmit_mixer.cc
diff --git a/webrtc/voice_engine/transmit_mixer.cc b/webrtc/voice_engine/transmit_mixer.cc
index 0240389be14f8df7132f1315087036baa199a49f..d6a5213217e3bfe92b36a3ddbf6b4f524f6ac0f3 100644
--- a/webrtc/voice_engine/transmit_mixer.cc
+++ b/webrtc/voice_engine/transmit_mixer.cc
@@ -205,6 +205,7 @@
     external_postproc_ptr_(NULL),
     external_preproc_ptr_(NULL),
     _mute(false),
+    _remainingMuteMicTimeMs(0),
     stereo_codec_(false),
     swap_stereo_channels_(false)
 {
@@ -358,6 +359,17 @@
     TypingDetection(keyPressed);
 #endif
 
+    // --- Mute during DTMF tone if direct feedback is enabled
+    if (_remainingMuteMicTimeMs > 0)
+    {
+        AudioFrameOperations::Mute(_audioFrame);
+        _remainingMuteMicTimeMs -= 10;
+        if (_remainingMuteMicTimeMs < 0)
+        {
+            _remainingMuteMicTimeMs = 0;
+        }
+    }
+
     // --- Mute signal
     if (_mute)
     {
@@ -463,6 +475,15 @@
 uint32_t TransmitMixer::CaptureLevel() const
 {
     return _captureLevel;
+}
+
+void
+TransmitMixer::UpdateMuteMicrophoneTime(uint32_t lengthMs)
+{
+    WEBRTC_TRACE(kTraceInfo, kTraceVoice, VoEId(_instanceId, -1),
+               "TransmitMixer::UpdateMuteMicrophoneTime(lengthMs=%d)",
+               lengthMs);
+    _remainingMuteMicTimeMs = lengthMs;
 }
 
 int32_t