Fixes crash bug when iterating through sessions in OnNetworkConnected.

net/quic/chromium/quic_stream_factory.cc

Index: net/quic/chromium/quic_stream_factory.cc
diff --git a/net/quic/chromium/quic_stream_factory.cc b/net/quic/chromium/quic_stream_factory.cc
index 38d76d789e5efef2266350b414d10e020308d136..6831339a35bf9fcfee1ffd37a0f6828a3a862e84 100644
--- a/net/quic/chromium/quic_stream_factory.cc
+++ b/net/quic/chromium/quic_stream_factory.cc
@@ -1265,8 +1265,12 @@ void QuicStreamFactory::OnNetworkConnected(NetworkHandle network) {
   status_ = OPEN;
   ScopedConnectionMigrationEventLog scoped_event_log(net_log_,
                                                      "OnNetworkConnected");
-  for (auto session : all_sessions_) {
-    session.first->OnNetworkConnected(network, scoped_event_log.net_log());
+  QuicStreamFactory::SessionIdMap::iterator it = all_sessions_.begin();
+  // Sessions may be deleted while iterating through the map.
+  while (it != all_sessions_.end()) {
+    QuicChromiumClientSession* session = it->first;
+    ++it;
+    session->OnNetworkConnected(network, scoped_event_log.net_log());
   }
 }