Convert channel counts to size_t.

webrtc/common_audio/include/audio_util.h

Index: webrtc/common_audio/include/audio_util.h
diff --git a/webrtc/common_audio/include/audio_util.h b/webrtc/common_audio/include/audio_util.h
index 2c0028ce90d637932366e8ccbf6e992689c6c6eb..55dfc06a316cc7546a84606e8e56621558b4c013 100644
--- a/webrtc/common_audio/include/audio_util.h
+++ b/webrtc/common_audio/include/audio_util.h
@@ -87,11 +87,11 @@ void CopyAudioIfNeeded(const T* const* src,
 template <typename T>
 void Deinterleave(const T* interleaved,
                   size_t samples_per_channel,
-                  int num_channels,
+                  size_t num_channels,
                   T* const* deinterleaved) {
-  for (int i = 0; i < num_channels; ++i) {
+  for (size_t i = 0; i < num_channels; ++i) {
     T* channel = deinterleaved[i];
-    int interleaved_idx = i;
+    size_t interleaved_idx = i;
     for (size_t j = 0; j < samples_per_channel; ++j) {
       channel[j] = interleaved[interleaved_idx];
       interleaved_idx += num_channels;
@@ -105,11 +105,11 @@ void Deinterleave(const T* interleaved,
 template <typename T>
 void Interleave(const T* const* deinterleaved,
                 size_t samples_per_channel,
-                int num_channels,
+                size_t num_channels,
                 T* interleaved) {
-  for (int i = 0; i < num_channels; ++i) {
+  for (size_t i = 0; i < num_channels; ++i) {
     const T* channel = deinterleaved[i];
-    int interleaved_idx = i;
+    size_t interleaved_idx = i;
     for (size_t j = 0; j < samples_per_channel; ++j) {
       interleaved[interleaved_idx] = channel[j];
       interleaved_idx += num_channels;