Pick the DTLS handshake timeout based on the ICE RTT estimate

webrtc/p2p/base/p2ptransportchannel.h

Index: webrtc/p2p/base/p2ptransportchannel.h
diff --git a/webrtc/p2p/base/p2ptransportchannel.h b/webrtc/p2p/base/p2ptransportchannel.h
index 2327b2d4771b776e3086fc484e12841257e6160f..4e9f0a31256e9cc5bf5fa7e42c7e491963276075 100644
--- a/webrtc/p2p/base/p2ptransportchannel.h
+++ b/webrtc/p2p/base/p2ptransportchannel.h
@@ -107,6 +107,7 @@ class P2PTransportChannel : public IceTransportInternal,
   bool GetOption(rtc::Socket::Option opt, int* value) override;
   int GetError() override { return error_; }
   bool GetStats(std::vector<ConnectionInfo>* stats) override;
+  rtc::Optional<int> GetRttEstimate() override;

[Taylor Brandstetter, 2017/02/02 18:07:41]

This method isn't really necessary, since the DTLS transport can call
"selected_connection()" and get its RTT directly.

But if you do decide to keep it, it should be named "GetSmoothedRtt", to avoid
confusion with "ConservativeRTTEstimate" (which returns the smoothed RTT times
2).

[pthatcher2, 2017/02/02 21:52:57]

I'd prefer that the DltsTransport only look at the IceTransport, and not thing
underneath.  It makes it easier to make changes later by staying decoupled.

 
   // TODO(honghaiz): Remove this method once the reference of it in
   // Chromoting is removed.