Require the new PACKET_KEEPALIVE_OFFLOAD permission.

Bug: 23884210
Change-Id: I50a1a647a69deaba92e73021ee7d6cc0f3eb1eee
diff --git a/services/core/java/com/android/server/connectivity/KeepaliveTracker.java b/services/core/java/com/android/server/connectivity/KeepaliveTracker.java
index 25ebf66..90c9ddf 100644
--- a/services/core/java/com/android/server/connectivity/KeepaliveTracker.java
+++ b/services/core/java/com/android/server/connectivity/KeepaliveTracker.java
@@ -62,8 +62,7 @@
     private static final String TAG = "KeepaliveTracker";
     private static final boolean DBG = true;
 
-    // TODO: Change this to a system-only permission.
-    public static final String PERMISSION = android.Manifest.permission.CHANGE_NETWORK_STATE;
+    public static final String PERMISSION = android.Manifest.permission.PACKET_KEEPALIVE_OFFLOAD;
 
     /** Keeps track of keepalive requests. */
     private final HashMap <NetworkAgentInfo, HashMap<Integer, KeepaliveInfo>> mKeepalives =