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

net/quic/quic_stream_factory.h

Index: net/quic/quic_stream_factory.h
diff --git a/net/quic/quic_stream_factory.h b/net/quic/quic_stream_factory.h
index 162607b54596afb93d21e235721f550e2336c9db..bc4cf975335d66597595dbb3ac486bbe8834b6cb 100644
--- a/net/quic/quic_stream_factory.h
+++ b/net/quic/quic_stream_factory.h
@@ -29,6 +29,8 @@
 #include "net/quic/quic_protocol.h"
 #include "net/ssl/ssl_config_service.h"
 
+using NetworkChangeNotifier::NetworkHandle;
+
 namespace net {
 
 class CertPolicyEnforcer;
@@ -105,6 +107,7 @@ class NET_EXPORT_PRIVATE QuicStreamRequest {
 // QuicChromiumClientSessions.
 class NET_EXPORT_PRIVATE QuicStreamFactory
     : public NetworkChangeNotifier::IPAddressObserver,
+      public NetworkChangeNotifier::NetworkObserver,
       public SSLConfigService::Observer,
       public CertDatabase::Observer {
  public:
@@ -206,6 +209,12 @@ class NET_EXPORT_PRIVATE QuicStreamFactory
   // IP address changes.
   void OnIPAddressChanged() override;
 
+  // NetworkChangeNotifier::NetworkObserver methods:
+  void OnNetworkConnected(NetworkHandle network) override;
+  void OnNetworkDisconnected(NetworkHandle network) override;
+  void OnNetworkSoonToDisconnect(NetworkHandle network) override;
+  void OnNetworkMadeDefault(NetworkHandle network) override;
+
   // SSLConfigService::Observer methods:
 
   // We perform the same flushing as described above when SSL settings change.