[NOT FOR REVIEW] Convert channel counts to size_t.

webrtc/modules/rtp_rtcp/interface/rtp_rtcp_defines.h

Index: webrtc/modules/rtp_rtcp/interface/rtp_rtcp_defines.h
diff --git a/webrtc/modules/rtp_rtcp/interface/rtp_rtcp_defines.h b/webrtc/modules/rtp_rtcp/interface/rtp_rtcp_defines.h
index ea366878c54281cd6279952cfec4392c4d350deb..d50d4e00c65616116621f4e6a3864116263382f3 100644
--- a/webrtc/modules/rtp_rtcp/interface/rtp_rtcp_defines.h
+++ b/webrtc/modules/rtp_rtcp/interface/rtp_rtcp_defines.h
@@ -33,7 +33,7 @@ const uint8_t kRtpHeaderSize = 12;
 struct AudioPayload
 {
     uint32_t    frequency;
-    uint8_t     channels;
+    size_t      channels;
     uint32_t    rate;
 };
 
@@ -243,7 +243,7 @@ public:
         const int8_t payloadType,
         const char payloadName[RTP_PAYLOAD_NAME_SIZE],
         const int frequency,
-        const uint8_t channels,
+        const size_t channels,
         const uint32_t rate) = 0;
 
     virtual void OnIncomingSSRCChanged( const int32_t id,
@@ -311,7 +311,7 @@ class NullRtpFeedback : public RtpFeedback {
                               const int8_t payloadType,
                               const char payloadName[RTP_PAYLOAD_NAME_SIZE],
                               const int frequency,
-                              const uint8_t channels,
+                              const size_t channels,
                               const uint32_t rate) override {
     return 0;
   }