Prepare to convert various types to size_t.

webrtc/common_audio/resampler/sinusoidal_linear_chirp_source.cc

 /*
  *  Copyright (c) 2013 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 18 matching lines @@
   k_ = (max_frequency_ - kMinFrequency) / duration;
 }
 
 void SinusoidalLinearChirpSource::Run(int frames, float* destination) {
   for (int i = 0; i < frames; ++i, ++current_index_) {
     // Filter out frequencies higher than Nyquist.
     if (Frequency(current_index_) > 0.5 * sample_rate_) {
       destination[i] = 0;
     } else {
       // Calculate time in seconds.
-      double t = (static_cast<double>(current_index_) - delay_samples_) /
-          sample_rate_;
-      if (t < 0) {
+      if (current_index_ < delay_samples_) {
         destination[i] = 0;
       } else {
         // Sinusoidal linear chirp.
+        double t = (current_index_ - delay_samples_) / sample_rate_;
         destination[i] =
             sin(2 * M_PI * (kMinFrequency * t + (k_ / 2) * t * t));
       }
     }
   }
 }
 
 double SinusoidalLinearChirpSource::Frequency(int position) {
   return kMinFrequency + (position - delay_samples_) *
       (max_frequency_ - kMinFrequency) / total_samples_;
 }
 
 }  // namespace webrtc