Early connection migration in QUIC.

net/quic/quic_sent_packet_manager.h

Index: net/quic/quic_sent_packet_manager.h
diff --git a/net/quic/quic_sent_packet_manager.h b/net/quic/quic_sent_packet_manager.h
index b0203df1173e9acac7fc2a82cc1c905e2188ff5b..f9e6bf4fec891931b0ff1031e19cd27d3ecedc71 100644
--- a/net/quic/quic_sent_packet_manager.h
+++ b/net/quic/quic_sent_packet_manager.h
@@ -102,6 +102,12 @@ class NET_EXPORT_PRIVATE QuicSentPacketManager {
     // Called when RTT may have changed, including when an RTT is read from
     // the config.
     virtual void OnRttChange() = 0;
+
+    // Called with the path may be degrading. Note that the path may only be
+    // temporarily degrading.
+    // TODO(jri): With multipath, this method should probably have a path_id
+    // parameter, and should maybe result in the path being marked as inactive.
+    virtual void OnPathDegrading() = 0;
   };
 
   QuicSentPacketManager(Perspective perspective,
@@ -232,6 +238,10 @@ class NET_EXPORT_PRIVATE QuicSentPacketManager {
   // Called when peer address changes and the connection migrates.
   void OnConnectionMigration(PeerAddressChangeType type);
 
+  // Used to determine if peer seems unresponsive. Note that the peer
+  // may only be temporarily unreachable.
+  bool IsPeerMaybeUnreachable() const;
+
   bool using_pacing() const { return using_pacing_; }
 
   void set_debug_delegate(DebugDelegate* debug_delegate) {