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

net/udp/datagram_client_socket.h

Index: net/udp/datagram_client_socket.h
diff --git a/net/udp/datagram_client_socket.h b/net/udp/datagram_client_socket.h
index ac4632ed2e33ff27fbf1a2a8fb7f3f365660e2fe..5a967475506f749239fdb8453d142b1f67820e47 100644
--- a/net/udp/datagram_client_socket.h
+++ b/net/udp/datagram_client_socket.h
@@ -25,6 +25,10 @@ class NET_EXPORT_PRIVATE DatagramClientSocket : public DatagramSocket,
   // Returns a net error code.
   virtual int BindToNetwork(NetworkChangeNotifier::NetworkHandle network) = 0;
 
+  // Same as BindToNetwork, except that the current default network is used.
+  // Returns a net error code.
+  virtual int BindToDefaultNetwork() = 0;

[Ryan Hamilton, 2015/11/18 22:23:36]

Are there other subclasses of this interface which you need to add this method
to?

[Jana, 2015/11/21 02:21:22]

There are two test classes that do need impls, and I'll need them when I start
writing tests. If Paul's CL
(https://codereview.chromium.org/1416213003/) doesn't land, I'll add those
temporarily in this CL to make progress (sorry for the mish-mash of CLs) 

+
   // Initialize this socket as a client socket to server at |address|.
   // Returns a network error code.
   virtual int Connect(const IPEndPoint& address) = 0;