Add NetworkChangeNotifier connectivity events to the NetLog.

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 731c305bebbf6279a0dd4e10d41488a3dbe4d3d4..21aa1a11cd14f3a0bcdfad8bde5d7a318549f93e 100644
--- a/net/base/network_change_notifier.h
+++ b/net/base/network_change_notifier.h
@@ -163,6 +163,9 @@ class NET_EXPORT NetworkChangeNotifier {
     NotifyObserversOfIPAddressChange();
   }
 
+  // Return a string equivalent to |type|.
+  static const char* ConnectionTypeToString(ConnectionType type);
+
   // Let the NetworkChangeNotifier know we received some data.
   // This is used strictly for producing histogram data about the accuracy of
   // the NetworkChangenotifier's online detection.