Update audio code to use size_t more correctly,

webrtc/modules/audio_coding/codecs/ilbc/frame_classify.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.
  */
 
 /******************************************************************
 
  iLBC Speech Coder ANSI-C Source Code
 
  WebRtcIlbcfix_FrameClassify.h
 
 ******************************************************************/
 
 #ifndef WEBRTC_MODULES_AUDIO_CODING_CODECS_ILBC_MAIN_SOURCE_FRAME_CLASSIFY_H_
 #define WEBRTC_MODULES_AUDIO_CODING_CODECS_ILBC_MAIN_SOURCE_FRAME_CLASSIFY_H_
 
-int16_t WebRtcIlbcfix_FrameClassify(
+size_t WebRtcIlbcfix_FrameClassify(
     /* (o) Index to the max-energy sub frame */
     IlbcEncoder *iLBCenc_inst,
     /* (i/o) the encoder state structure */
     int16_t *residualFIX /* (i) lpc residual signal */
                                                 );
 
 #endif