Prepare to convert various types to size_t.

webrtc/common_audio/audio_converter_unittest.cc

Index: webrtc/common_audio/audio_converter_unittest.cc
diff --git a/webrtc/common_audio/audio_converter_unittest.cc b/webrtc/common_audio/audio_converter_unittest.cc
index 6da339f08a09e4672a22515a386a28ca30c20216..590c8ceb56afeb2d3aa5227da98b7ebf4fb39d67 100644
--- a/webrtc/common_audio/audio_converter_unittest.cc
+++ b/webrtc/common_audio/audio_converter_unittest.cc
@@ -49,7 +49,7 @@ float ComputeSNR(const ChannelBuffer<float>& ref,
   int best_delay = 0;
 
   // Search within one sample of the expected delay.
-  for (int delay = std::max(expected_delay - 1, 0);
+  for (int delay = std::max(expected_delay, 1) - 1;
        delay <= std::min(expected_delay + 1, ref.num_frames());
        ++delay) {
     float mse = 0;