[NOT FOR REVIEW] Convert channel counts to size_t.

webrtc/modules/audio_processing/beamformer/nonlinear_beamformer_test.cc

Index: webrtc/modules/audio_processing/beamformer/nonlinear_beamformer_test.cc
diff --git a/webrtc/modules/audio_processing/beamformer/nonlinear_beamformer_test.cc b/webrtc/modules/audio_processing/beamformer/nonlinear_beamformer_test.cc
index 82a6cb050bc3ae1f2e1e0033633dca042c18e6ec..c08eb8ce70a044219b3886a5d32325a88a0f0b4a 100644
--- a/webrtc/modules/audio_processing/beamformer/nonlinear_beamformer_test.cc
+++ b/webrtc/modules/audio_processing/beamformer/nonlinear_beamformer_test.cc
@@ -12,6 +12,7 @@
 
 #include "gflags/gflags.h"
 #include "webrtc/base/checks.h"
+#include "webrtc/base/format_macros.h"
 #include "webrtc/common_audio/channel_buffer.h"
 #include "webrtc/common_audio/wav_file.h"
 #include "webrtc/modules/audio_processing/beamformer/nonlinear_beamformer.h"
@@ -52,9 +53,9 @@ int main(int argc, char* argv[]) {
   NonlinearBeamformer bf(array_geometry);
   bf.Initialize(kChunkSizeMs, in_file.sample_rate());
 
-  printf("Input file: %s\nChannels: %d, Sample rate: %d Hz\n\n",
+  printf("Input file: %s\nChannels: %" PRIuS ", Sample rate: %d Hz\n\n",
          FLAGS_i.c_str(), in_file.num_channels(), in_file.sample_rate());
-  printf("Output file: %s\nChannels: %d, Sample rate: %d Hz\n\n",
+  printf("Output file: %s\nChannels: %" PRIuS ", Sample rate: %d Hz\n\n",
          FLAGS_o.c_str(), out_file.num_channels(), out_file.sample_rate());
 
   ChannelBuffer<float> in_buf(