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

net/base/network_change_notifier.h

Index: net/base/network_change_notifier.h
diff --git a/net/base/network_change_notifier.h b/net/base/network_change_notifier.h
index 7ebff810346c01c9726d2261aefc1afbae3a0563..6013fa156f8689aa617f386a61137fdb028dcdf0 100644
--- a/net/base/network_change_notifier.h
+++ b/net/base/network_change_notifier.h
@@ -101,6 +101,15 @@ class NET_EXPORT NetworkChangeNotifier {
     SUBTYPE_LAST = SUBTYPE_OTHER
   };
 
+  // Types of network changes specified to
+  // NotifyObserversOfSpecificNetworkChange.
+  enum NetworkChangeType {
+    CONNECTED,
+    DISCONNECTED,
+    SOON_TO_DISCONNECT,
+    MADE_DEFAULT
+  };
+
   class NET_EXPORT IPAddressObserver {
    public:
     // Will be called when the IP address of the primary interface changes.
@@ -389,6 +398,9 @@ class NET_EXPORT NetworkChangeNotifier {
   static void NotifyObserversOfConnectionTypeChangeForTests(
       ConnectionType type);
   static void NotifyObserversOfNetworkChangeForTests(ConnectionType type);
+  static void NotifyObserversOfSpecificNetworkChangeForTests(
+      NetworkChangeType type,
+      NetworkHandle network);
   static void NotifyObserversOfInitialDNSConfigReadForTests();
   static void NotifyObserversOfMaxBandwidthChangeForTests(
       double max_bandwidth_mbps,
@@ -440,15 +452,6 @@ class NET_EXPORT NetworkChangeNotifier {
   };
 
  protected:
-  // Types of network changes specified to
-  // NotifyObserversOfSpecificNetworkChange.
-  enum NetworkChangeType {
-    CONNECTED,
-    DISCONNECTED,
-    SOON_TO_DISCONNECT,
-    MADE_DEFAULT
-  };
-
   // NetworkChanged signal is calculated from the IPAddressChanged and
   // ConnectionTypeChanged signals. Delay parameters control how long to delay
   // producing NetworkChanged signal after particular input signals so as to