Expose RtpCodecParameters to VoiceMediaInfo stats.

webrtc/media/engine/webrtcvideoengine2.cc

Index: webrtc/media/engine/webrtcvideoengine2.cc
diff --git a/webrtc/media/engine/webrtcvideoengine2.cc b/webrtc/media/engine/webrtcvideoengine2.cc
index c43dff80d3d140f87334f482df5ae266026c4832..01a1161197f05a27a9338305bb32dee96faadbd1 100644
--- a/webrtc/media/engine/webrtcvideoengine2.cc
+++ b/webrtc/media/engine/webrtcvideoengine2.cc
@@ -1409,13 +1409,17 @@ void WebRtcVideoChannel2::FillSendAndReceiveCodecStats(
     VideoMediaInfo* video_media_info) {
   for (const VideoCodec& codec : send_params_.codecs) {
     webrtc::RtpCodecParameters codec_params = codec.ToCodecParameters();
+    RTC_DCHECK_GE(codec_params.payload_type, 0);

[the sun, 2016/11/16 19:41:07]

Why are you DCHECKing this property here?

If the reason is just because of the cast to unsigned, change the map key type
to int instead.

If you want to make sure the payload type is something sane, you should also
check that it is <= 127 - and then it would be better to move the check into
RtpCodecParameters (making the field const, and adding DCHECks in the ctor) so
we don't have to remember DCHECKing in all places where we use the field.

[hbos, 2016/11/17 14:14:48]

Since RtpCodecParameter and the data structure it gets its value from all use
int, I'll make this code use int too.

Modifying it to DHCECK in its constructor is a good idea but just making its
members const removes the copy assignment operator and breaks code using
std::vector<RtpCodecParameter>. I don't want to do a bunch of refactoring in
this CL, so I'm just using int, this CL does not depend on the range of the
value anymore.

     video_media_info->send_codecs.insert(
-        std::make_pair(codec_params.payload_type, std::move(codec_params)));
+        std::make_pair(static_cast<uint32_t>(codec_params.payload_type),
+                       std::move(codec_params)));
   }
   for (const VideoCodec& codec : recv_params_.codecs) {
     webrtc::RtpCodecParameters codec_params = codec.ToCodecParameters();
+    RTC_DCHECK_GE(codec_params.payload_type, 0);
     video_media_info->receive_codecs.insert(
-        std::make_pair(codec_params.payload_type, std::move(codec_params)));
+        std::make_pair(static_cast<uint32_t>(codec_params.payload_type),
+                       std::move(codec_params)));
   }
 }