Report interframe delay sum in old GetStats

webrtc/media/base/mediachannel.h

Index: webrtc/media/base/mediachannel.h
diff --git a/webrtc/media/base/mediachannel.h b/webrtc/media/base/mediachannel.h
index de2a7cdd4ef3b6084e67a7183df8f34e69970a63..1109f562053ead3f099a15da8d39790064e3ebb3 100644
--- a/webrtc/media/base/mediachannel.h
+++ b/webrtc/media/base/mediachannel.h
@@ -741,6 +741,7 @@ struct VideoReceiverInfo : public MediaReceiverInfo {
         frames_received(0),
         frames_decoded(0),
         frames_rendered(0),
+        interframe_delay_sum_ms(0),
         decode_ms(0),
         max_decode_ms(0),
         jitter_buffer_ms(0),
@@ -770,6 +771,7 @@ struct VideoReceiverInfo : public MediaReceiverInfo {
   uint32_t frames_decoded;
   uint32_t frames_rendered;
   rtc::Optional<uint64_t> qp_sum;
+  uint64_t interframe_delay_sum_ms;
 
   // All stats below are gathered per-VideoReceiver, but some will be correlated
   // across MediaStreamTracks.  NOTE(hta): when sinking stats into per-SSRC