Early connection migration in QUIC.

net/quic/quic_connection.h

Index: net/quic/quic_connection.h
diff --git a/net/quic/quic_connection.h b/net/quic/quic_connection.h
index 85a8ee4ea3b29b974e9da595d76a866835436ef4..3a4e98a8479b95765a8ca4ac4e44a1931b1cfeb4 100644
--- a/net/quic/quic_connection.h
+++ b/net/quic/quic_connection.h
@@ -137,6 +137,9 @@ class NET_EXPORT_PRIVATE QuicConnectionVisitorInterface {
   // been done.
   virtual void PostProcessAfterData() = 0;
 
+  // Called when the the peer seems unreachable over the current path.
+  virtual void OnPathDegrading() = 0;

[Ryan Hamilton, 2016/02/04 20:22:20]

Isn't this part of the internal CL? Can you exclude the diffs from that CL here?

+
   // Called to ask if the visitor wants to schedule write resumption as it both
   // has pending data to write, and is able to write (e.g. based on flow control
   // limits).
@@ -465,6 +468,7 @@ class NET_EXPORT_PRIVATE QuicConnection
   // QuicSentPacketManager::NetworkChangeVisitor
   void OnCongestionWindowChange() override;
   void OnRttChange() override;
+  void OnPathDegrading() override;
 
   // Called by the crypto stream when the handshake completes. In the server's
   // case this is when the SHLO has been ACKed. Clients call this on receipt of