Update audio code to use size_t more correctly,

webrtc/modules/audio_processing/vad/pitch_based_vad.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 57 matching lines @@
   double p;
   double gmm_features[3];
   double pdf_features_given_voice;
   double pdf_features_given_noise;
   // These limits are the same in matlab implementation 'VoicingProbGMM().'
   const double kLimLowLogPitchGain = -2.0;
   const double kLimHighLogPitchGain = -0.9;
   const double kLimLowSpectralPeak = 200;
   const double kLimHighSpectralPeak = 2000;
   const double kEps = 1e-12;
-  for (int n = 0; n < features.num_frames; n++) {
+  for (size_t n = 0; n < features.num_frames; n++) {
     gmm_features[0] = features.log_pitch_gain[n];
     gmm_features[1] = features.spectral_peak[n];
     gmm_features[2] = features.pitch_lag_hz[n];
 
     pdf_features_given_voice = EvaluateGmm(gmm_features, voice_gmm_);
     pdf_features_given_noise = EvaluateGmm(gmm_features, noise_gmm_);
 
     if (features.spectral_peak[n] < kLimLowSpectralPeak ||
         features.spectral_peak[n] > kLimHighSpectralPeak ||
         features.log_pitch_gain[n] < kLimLowLogPitchGain) {
@@ skipping 26 matching lines @@
 int PitchBasedVad::UpdatePrior(double p) {
   circular_buffer_->Insert(p);
   if (circular_buffer_->RemoveTransient(kTransientWidthThreshold,
                                         kLowProbabilityThreshold) < 0)
     return -1;
   p_prior_ = circular_buffer_->Mean();
   return 0;
 }
 
 }  // namespace webrtc