Map TYPE_VPN integer to "VPN" string.

Bug: 18439110
Change-Id: I0fa0c9e6a9293ab724e2b5e7d0f586f05cd100c7
diff --git a/core/java/android/net/ConnectivityManager.java b/core/java/android/net/ConnectivityManager.java
index ec24ded..06e8157 100644
--- a/core/java/android/net/ConnectivityManager.java
+++ b/core/java/android/net/ConnectivityManager.java
@@ -509,6 +509,8 @@
                 return "MOBILE_EMERGENCY";
             case TYPE_PROXY:
                 return "PROXY";
+            case TYPE_VPN:
+                return "VPN";
             default:
                 return Integer.toString(type);
         }