First pass at USB Tethering.

bug:2281900
diff --git a/core/java/android/provider/Settings.java b/core/java/android/provider/Settings.java
index 7128005..bacaf43 100644
--- a/core/java/android/provider/Settings.java
+++ b/core/java/android/provider/Settings.java
@@ -2944,6 +2944,13 @@
         public static final String MOUNT_UMS_NOTIFY_ENABLED = "mount_ums_notify_enabled";
 
         /**
+         * Whether or not a notification is displayed when a Tetherable interface is detected.
+         * (0 = false, 1 = true)
+         * @hide
+         */
+        public static final String TETHER_NOTIFY = "tether_notify";
+
+        /**
          * If nonzero, ANRs in invisible background processes bring up a dialog.
          * Otherwise, the process will be silently killed.
          * @hide