Start default connections on startup.

On devices with mobile data we were kind of doing this in Telephony.
Devices without could use this.

bug:5030831
Change-Id: I9940561e88e43917bc8e638f5c3b15fced3821ae
diff --git a/services/java/com/android/server/ConnectivityService.java b/services/java/com/android/server/ConnectivityService.java
index eaaf8c2..7812927 100644
--- a/services/java/com/android/server/ConnectivityService.java
+++ b/services/java/com/android/server/ConnectivityService.java
@@ -484,6 +484,7 @@
                 continue;
             }
             mCurrentLinkProperties[netType] = null;
+            if (mNetConfigs[netType].isDefault()) mNetTrackers[netType].reconnect();
         }
 
         IBinder b = ServiceManager.getService(Context.NETWORKMANAGEMENT_SERVICE);