[NOT FOR REVIEW] Convert channel counts to size_t.

webrtc/voice_engine/output_mixer.h

 /*
  *  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 45 matching lines @@
     int32_t MixActiveChannels();
 
     int32_t DoOperationsOnCombinedSignal(bool feed_data_to_apm);
 
     int32_t SetMixabilityStatus(MixerParticipant& participant,
                                 bool mixable);
 
     int32_t SetAnonymousMixabilityStatus(MixerParticipant& participant,
                                          bool mixable);
 
-    int GetMixedAudio(int sample_rate_hz, int num_channels,
+    int GetMixedAudio(int sample_rate_hz, size_t num_channels,
                       AudioFrame* audioFrame);
 
     // VoEVolumeControl
     int GetSpeechOutputLevel(uint32_t& level);
 
     int GetSpeechOutputLevelFullRange(uint32_t& level);
 
     int SetOutputVolumePan(float left, float right);
 
     int GetOutputVolumePan(float& left, float& right);
@@ skipping 52 matching lines @@
     int _mixingFrequencyHz;
     FileRecorder* _outputFileRecorderPtr;
     bool _outputFileRecording;
 };
 
 }  // namespace voe
 
 }  // namespace werbtc
 
 #endif  // VOICE_ENGINE_OUTPUT_MIXER_H_