Migrates QUIC sessions to a new network when old network is (about to be) disconnected.

net/quic/quic_protocol.h

Index: net/quic/quic_protocol.h
diff --git a/net/quic/quic_protocol.h b/net/quic/quic_protocol.h
index 7029687a16f28ba89a394de91db97dcf3aa846da..4bc87c50fbaa656f61d74cde24020f42c4603679 100644
--- a/net/quic/quic_protocol.h
+++ b/net/quic/quic_protocol.h
@@ -634,8 +634,20 @@ enum QuicErrorCode {
   // tampered with.
   QUIC_VERSION_NEGOTIATION_MISMATCH = 55,
 
+  // IP address changed causing connection close.
+  QUIC_IP_ADDRESS_CHANGED = 77,

[Ryan Hamilton, 2015/12/18 21:51:23]

Do we expect this to go away in favor of the MIGRATION ones?

[Jana, 2015/12/21 23:10:19]

Eventually, on Android devices. But we don't yet have the MIGRATION
notifications for non-Android devices, so this will remain around for the
platforms where IPAddressChanged exists. I know that set is larger than
{Android}, but I don't know what else it contains.

+
+  // Connection migration errors.
+  // Network changed, but connection had no migratable streams.
+  QUIC_CONNECTION_MIGRATION_NO_MIGRATABLE_STREAMS = 78,

[Ryan Hamilton, 2015/12/18 21:51:23]

How different is this from IP_ADDRESS_CHANGED?

[Jana, 2015/12/21 23:10:19]

This is when migration could have happened, but didn't because there were no
"active" streams. It's different in that IP_ADDRESS_CHANGED means active streams
may have been reset, but here, there were no active streams. Make sense?

+  // Connection changed networks too many times.
+  QUIC_CONNECTION_MIGRATION_TOO_MANY_CHANGES = 79,
+  // Connection migration was attempted, but there was no new network to
+  // migrate to.
+  QUIC_CONNECTION_MIGRATION_NO_NEW_NETWORK = 80,
+
   // No error. Used as bound while iterating.
-  QUIC_LAST_ERROR = 77,
+  QUIC_LAST_ERROR = 81,
 };
 
 // Must be updated any time a QuicErrorCode is deprecated.