Reduce log level in BaseChannel::SendPacket.

This log line is causing test failures due to excessive logging (see
referenced bug); reducing log level.

Bug: chromium:984879
Change-Id: Ic94ba0a39b91b4253a58ad54de0cba1ca49882e2
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/175913
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Commit-Queue: Marina Ciocea <marinaciocea@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#31803}
diff --git a/pc/channel.cc b/pc/channel.cc
index e7f62c6..eeba19b 100644
--- a/pc/channel.cc
+++ b/pc/channel.cc
@@ -434,9 +434,9 @@
     }
 
     std::string packet_type = rtcp ? "RTCP" : "RTP";
-    RTC_LOG(LS_WARNING) << "Sending an " << packet_type
-                        << " packet without encryption for " << ToString()
-                        << ".";
+    RTC_DLOG(LS_WARNING) << "Sending an " << packet_type
+                         << " packet without encryption for " << ToString()
+                         << ".";
   }
 
   // Bon voyage.