[NOT FOR REVIEW] Convert channel counts to size_t.

webrtc/modules/audio_coding/main/acm2/audio_coding_module.cc

Index: webrtc/modules/audio_coding/main/acm2/audio_coding_module.cc
diff --git a/webrtc/modules/audio_coding/main/acm2/audio_coding_module.cc b/webrtc/modules/audio_coding/main/acm2/audio_coding_module.cc
index 51b9a78896130a263339554269d08d091601fd08..a16f14a0524d03c08c0b6a42fc402933d4a43654 100644
--- a/webrtc/modules/audio_coding/main/acm2/audio_coding_module.cc
+++ b/webrtc/modules/audio_coding/main/acm2/audio_coding_module.cc
@@ -53,7 +53,7 @@ int AudioCodingModule::Codec(int list_id, CodecInst* codec) {
 int AudioCodingModule::Codec(const char* payload_name,
                              CodecInst* codec,
                              int sampling_freq_hz,
-                             int channels) {
+                             size_t channels) {
   int codec_id;
 
   // Get the id of the codec from the database.
@@ -83,7 +83,7 @@ int AudioCodingModule::Codec(const char* payload_name,
 // Get supported codec Index with name, frequency and number of channels.
 int AudioCodingModule::Codec(const char* payload_name,
                              int sampling_freq_hz,
-                             int channels) {
+                             size_t channels) {
   return acm2::ACMCodecDB::CodecId(payload_name, sampling_freq_hz, channels);
 }