Reinstate USER_PRESENT for ConnectivityService

Reverts half of commit 829f7c72e5
Reverts parts of commit 9b747914f3

Lockdown VPN still needs this to start properly on devices without FBE,
such as phones upgraded from M. Without listening to USER_PRESENT the
first unlock of keystore may get missed, since USER_UNLOCKED is sent too
soon to be useful.

Bug: 34587043
Change-Id: If7a2f5a3173b0f6856244a5f7904bf00c9a5b5e7

services/core/java/com/android/server/ConnectivityService.java

@@ -815,6 +815,8 @@ public class ConnectivityService extends IConnectivityManager.Stub
         intentFilter.addAction(Intent.ACTION_USER_UNLOCKED);
         mContext.registerReceiverAsUser(
                 mUserIntentReceiver, UserHandle.ALL, intentFilter, null, null);
+        mContext.registerReceiverAsUser(mUserPresentReceiver, UserHandle.SYSTEM,
+                new IntentFilter(Intent.ACTION_USER_PRESENT), null, null);
 
         try {
             mNetd.registerObserver(mTethering);
@@ -4000,6 +4002,16 @@ public class ConnectivityService extends IConnectivityManager.Stub
         }
     };
 
+    private BroadcastReceiver mUserPresentReceiver = new BroadcastReceiver() {
+        @Override
+        public void onReceive(Context context, Intent intent) {
+            // Try creating lockdown tracker, since user present usually means
+            // unlocked keystore.
+            updateLockdownVpn();
+            mContext.unregisterReceiver(this);
+        }
+    };
+
     private final HashMap<Messenger, NetworkFactoryInfo> mNetworkFactoryInfos =
             new HashMap<Messenger, NetworkFactoryInfo>();
     private final HashMap<NetworkRequest, NetworkRequestInfo> mNetworkRequests =