Match existing type usage better.

webrtc/common_audio/real_fourier.cc

 /*
  *  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.
  */
 
@@ skipping 13 matching lines @@
 rtc::scoped_ptr<RealFourier> RealFourier::Create(int fft_order) {
 #if defined(RTC_USE_OPENMAX_DL)
   return rtc::scoped_ptr<RealFourier>(new RealFourierOpenmax(fft_order));
 #else
   return rtc::scoped_ptr<RealFourier>(new RealFourierOoura(fft_order));
 #endif
 }
 
 int RealFourier::FftOrder(int length) {
   CHECK_GT(length, 0);
-  return WebRtcSpl_GetSizeInBits(length - 1);
+  return WebRtcSpl_GetSizeInBits(static_cast<uint32_t>(length - 1));
 }
 
 int RealFourier::FftLength(int order) {
   CHECK_GE(order, 0);
   return 1 << order;
 }
 
 int RealFourier::ComplexLength(int order) {
   return FftLength(order) / 2 + 1;
 }
 
 RealFourier::fft_real_scoper RealFourier::AllocRealBuffer(int count) {
   return fft_real_scoper(static_cast<float*>(
       AlignedMalloc(sizeof(float) * count, kFftBufferAlignment)));
 }
 
 RealFourier::fft_cplx_scoper RealFourier::AllocCplxBuffer(int count) {
   return fft_cplx_scoper(static_cast<complex<float>*>(
       AlignedMalloc(sizeof(complex<float>) * count, kFftBufferAlignment)));
 }
 
 }  // namespace webrtc