Revert of Remove ignored return code from modules.

webrtc/voice_engine/monitor_module.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 39 matching lines @@
 }
 
 int64_t
 MonitorModule::TimeUntilNextProcess()
 {
     int64_t now = TickTime::MillisecondTimestamp();
     const int64_t kAverageProcessUpdateTimeMs = 1000;
     return kAverageProcessUpdateTimeMs - (now - _lastProcessTime);
 }
 
-void
+int32_t
 MonitorModule::Process()
 {
     _lastProcessTime = TickTime::MillisecondTimestamp();
     rtc::CritScope lock(&_callbackCritSect);
     if (_observerPtr)
     {
         _observerPtr->OnPeriodicProcess();
     }
+    return 0;
 }
 
 }  // namespace voe
 
 }  // namespace webrtc