Pick the DTLS handshake timeout based on the ICE RTT estimate

webrtc/p2p/base/p2ptransportchannel.cc

Index: webrtc/p2p/base/p2ptransportchannel.cc
diff --git a/webrtc/p2p/base/p2ptransportchannel.cc b/webrtc/p2p/base/p2ptransportchannel.cc
index f47f03bbd64f7276e7887f152941539799c80c22..2f1f4477a3297429172aea53dbbf2b8e7b87bf78 100644
--- a/webrtc/p2p/base/p2ptransportchannel.cc
+++ b/webrtc/p2p/base/p2ptransportchannel.cc
@@ -276,6 +276,14 @@ IceTransportState P2PTransportChannel::GetState() const {
   return state_;
 }
 
+rtc::Optional<int> P2PTransportChannel::GetRttEstimate() {
+  if (selected_connection_ != nullptr) {
+    return rtc::Optional<int>(selected_connection_->rtt());
+  } else {
+    return rtc::Optional<int>();
+  }
+}
+
 // A channel is considered ICE completed once there is at most one active
 // connection per network and at least one active connection.
 IceTransportState P2PTransportChannel::ComputeState() const {