Update audio code to use size_t more correctly, webrtc/common_audio/ portion.

webrtc/common_audio/window_generator.h

 /*
  *  Copyright (c) 2014 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.
  */
 
 #ifndef WEBRTC_COMMON_AUDIO_WINDOW_GENERATOR_H_
 #define WEBRTC_COMMON_AUDIO_WINDOW_GENERATOR_H_
 
+#include <stddef.h>
+
 #include "webrtc/base/constructormagic.h"
 
 namespace webrtc {
 
 // Helper class with generators for various signal transform windows.
 class WindowGenerator {
  public:
   static void Hanning(int length, float* window);
-  static void KaiserBesselDerived(float alpha, int length, float* window);
+  static void KaiserBesselDerived(float alpha, size_t length, float* window);
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(WindowGenerator);
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_COMMON_AUDIO_WINDOW_GENERATOR_H_