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

net/udp/udp_client_socket.cc

Index: net/udp/udp_client_socket.cc
diff --git a/net/udp/udp_client_socket.cc b/net/udp/udp_client_socket.cc
index ca1f9e2439dd68c9f623a8b416dc5c9ae2372873..fb8f54806b4e95b21b24fba15c2786befebac952 100644
--- a/net/udp/udp_client_socket.cc
+++ b/net/udp/udp_client_socket.cc
@@ -24,6 +24,12 @@ int UDPClientSocket::BindToNetwork(
   return socket_.BindToNetwork(network);
 }
 
+int UDPClientSocket::BindToDefaultNetwork() {
+  NetworkChangeNotifier::NetworkHandle network = 
+      NetworkChangeNotifier::GetDefaultNetwork();
+  return BindToNetwork(network);

[pauljensen, 2015/10/19 19:01:39]

The reason this needs to loop is that the default network can change, so this is
racy.  The idea is to do something like:
int ret;
for (int attempt = 0; attempt < 3; attempt++) {
  NetworkChangeNotifier::NetworkHandle network =
      NetworkChangeNotifier::GetDefaultNetwork();
  if (network == kInvalidNetworkHandle)
    return ERR_INTERNET_DISCONNECTED;
  ret = BindToNetwork(network);
  if (ret != /*whatever ENONET turns into*/)
    return ret;
}
return ret;

You can see we return ENONET when we try to bind a socket to a network that no
longer exists here in Android:
http://androidxref.com/6.0.0_r1/xref/system/netd/server/NetworkController.cpp...

[pauljensen, 2015/10/19 19:49:04]

This incorrectly returns ERR_INTERNET_DISCONNECTED however when
GetDefaultNetwork isn't implemented however...hmm

[Jana, 2015/11/17 01:50:09]

Let's continue this conversation on your CL to implement BindToDefaultNetwork.
I'm leaving this simple implementation as is, to be replaced by your
implementation. SG?

+}
+
 int UDPClientSocket::Connect(const IPEndPoint& address) {
   int rv = socket_.Open(address.GetFamily());
   if (rv != OK)