Ignore system apps on enforceMeteredApnPolicy().

BUG: 29514913
Fixes: 29448383
Change-Id: I19eb004c937e1c872bbf82caa7a919e43d48a259
diff --git a/services/core/java/com/android/server/ConnectivityService.java b/services/core/java/com/android/server/ConnectivityService.java
index 130fb7c..b12972c 100644
--- a/services/core/java/com/android/server/ConnectivityService.java
+++ b/services/core/java/com/android/server/ConnectivityService.java
@@ -30,8 +30,6 @@
 import static android.net.NetworkCapabilities.NET_CAPABILITY_VALIDATED;
 import static android.net.NetworkPolicyManager.RULE_ALLOW_ALL;
 import static android.net.NetworkPolicyManager.RULE_ALLOW_METERED;
-import static android.net.NetworkPolicyManager.MASK_METERED_NETWORKS;
-import static android.net.NetworkPolicyManager.MASK_ALL_NETWORKS;
 import static android.net.NetworkPolicyManager.RULE_NONE;
 import static android.net.NetworkPolicyManager.RULE_REJECT_ALL;
 import static android.net.NetworkPolicyManager.RULE_REJECT_METERED;
@@ -921,7 +919,7 @@
         // Networks aren't blocked when ignoring blocked status
         if (ignoreBlocked) return false;
         // Networks are never blocked for system services
-        if (uid < Process.FIRST_APPLICATION_UID) return false;
+        if (isSystem(uid)) return false;
 
         final boolean networkMetered;
         final int uidRules;
@@ -4032,12 +4030,18 @@
         return false;
     }
 
+    private boolean isSystem(int uid) {
+        return uid < Process.FIRST_APPLICATION_UID;
+    }
 
     private void enforceMeteredApnPolicy(NetworkCapabilities networkCapabilities) {
+        final int uid = Binder.getCallingUid();
+        if (isSystem(uid)) {
+            return;
+        }
         // if UID is restricted, don't allow them to bring up metered APNs
         if (networkCapabilities.hasCapability(NET_CAPABILITY_NOT_METERED) == false) {
             final int uidRules;
-            final int uid = Binder.getCallingUid();
             synchronized(mRulesLock) {
                 uidRules = mUidRules.get(uid, RULE_ALLOW_ALL);
             }