Revert of Remove ignored return code from modules.

webrtc/voice_engine/output_mixer.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.
  */
 
@@ skipping 206 matching lines @@
 int32_t
 OutputMixer::SetAnonymousMixabilityStatus(MixerParticipant& participant,
                                           bool mixable)
 {
     return _mixerModule.SetAnonymousMixabilityStatus(&participant, mixable);
 }
 
 int32_t
 OutputMixer::MixActiveChannels()
 {
-    _mixerModule.Process();
-    return 0;
+    return _mixerModule.Process();
 }
 
 int
 OutputMixer::GetSpeechOutputLevel(uint32_t& level)
 {
     int8_t currentLevel = _audioLevel.Level();
     level = static_cast<uint32_t> (currentLevel);
     WEBRTC_TRACE(kTraceStateInfo, kTraceVoice, VoEId(_instanceId,-1),
                  "GetSpeechOutputLevel() => level=%u", level);
     return 0;
@@ skipping 359 matching lines @@
             _audioFrame.data_[2 * i + 1] = 0;
         }
     }
     assert(_audioFrame.samples_per_channel_ == toneSamples);
 
     return 0;
 }
 
 }  // namespace voe
 }  // namespace webrtc