Convert channel counts to size_t.

webrtc/modules/rtp_rtcp/include/rtp_rtcp_defines.h

Index: webrtc/modules/rtp_rtcp/include/rtp_rtcp_defines.h
diff --git a/webrtc/modules/rtp_rtcp/include/rtp_rtcp_defines.h b/webrtc/modules/rtp_rtcp/include/rtp_rtcp_defines.h
index d2ac62e8453940cf5ab175f5b1b7bd8886ed2a65..fad97f19cc5731a72bca6149517c8d586551ed90 100644
--- a/webrtc/modules/rtp_rtcp/include/rtp_rtcp_defines.h
+++ b/webrtc/modules/rtp_rtcp/include/rtp_rtcp_defines.h
@@ -35,7 +35,7 @@ const uint8_t kRtpHeaderSize = 12;
 
 struct AudioPayload {
     uint32_t    frequency;
-    uint8_t     channels;
+    size_t      channels;

[the sun, 2016/01/07 12:27:59]

On 64-bit machines member alignment rules will cause this struct to be 30%
bigger. Probably not an issue, but it could be avoided by moving 'channels' to
be the first member.

Other structs touched by this CL would likely be affected in similar ways.

[Peter Kasting, 2016/01/07 13:14:41]

It looks like other places (e.g. the param list of OnInitializeDecoder() below)
use the same param ordering.  If I changed one I'd kind of like to change the
others to be consistent.  That could be a lot of places.

Realistically, are there going to be tens of thousands or more of these objects,
such that the additional bytes would add up to a meaningful amount?

[the sun, 2016/01/07 13:21:06]

I don't see why the order of parameters necessarily need to be the same as the
order of fields in a data type. If all fields of the type are passed as params,
why not pass the struct instead?
In this case I definitely doubt it would be noticeable. What other structs are
affected, and by how much? Also, there's always the rule about premature
pessimisation. :)

[Peter Kasting, 2016/01/07 22:28:39]

I think that makes sense, but it's a bit of refactoring that goes beyond the
scope of what I want to do in this patch.
Don't know, but I can't imagine it's anything meaningful, since I'm changing the
type of channel counts, and there's shouldn't be any structs with a "number of
channels" member that are copied many times (e.g. actual audio packets wouldn't
have such a member).

     uint32_t    rate;
 };
 
@@ -210,7 +210,7 @@ class 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) = 0;
 
   virtual void OnIncomingSSRCChanged(const uint32_t ssrc) = 0;
@@ -333,7 +333,7 @@ class NullRtpFeedback : public RtpFeedback {
   int32_t OnInitializeDecoder(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;
   }