Don't log warning for unexpected STUN binding responses.

It was too spammy in the log because we have many code paths that check for responses when it's not a problem that it's not an expected response.

R=glaznev@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/47199004

Cr-Commit-Position: refs/heads/master@{#9212}
diff --git a/webrtc/p2p/base/stunrequest.cc b/webrtc/p2p/base/stunrequest.cc
index e3f21df..c5700c0 100644
--- a/webrtc/p2p/base/stunrequest.cc
+++ b/webrtc/p2p/base/stunrequest.cc
@@ -78,8 +78,8 @@
 bool StunRequestManager::CheckResponse(StunMessage* msg) {
   RequestMap::iterator iter = requests_.find(msg->transaction_id());
   if (iter == requests_.end()) {
-    LOG(LS_WARNING) << "Ignoring STUN response for unknown request "
-                    << rtc::hex_encode(msg->transaction_id());
+    // TODO(pthatcher): Log unknown responses without being too spammy
+    // in the logs.
     return false;
   }
 
@@ -111,8 +111,8 @@
 
   RequestMap::iterator iter = requests_.find(id);
   if (iter == requests_.end()) {
-    LOG(LS_WARNING) << "Ignoring STUN response for unknown request "
-                    << rtc::hex_encode(id);
+    // TODO(pthatcher): Log unknown responses without being too spammy
+    // in the logs.
     return false;
   }