Remove useless code

The semantics of this block are such that restart will
only be false if all components of mArguments are null.
mArguments is a final array initialized in the
constructor of LegacyVpnRunner. The components of the
array are never overwritten (though the components of
those components are), and at least one of these
components will always be non-null (unless somebody
calls startLegacyVpnPrivileged with a non-existing
type, but that never happens).

For safety, this patch also adds a check so that
the code will crash early with a clear message if this
ever happens.

Test: FrameworksNetTests NetworkStackTests
Change-Id: I1f13aa08c6f1870c9610185b603af76f97c22bab

services/core/java/com/android/server/connectivity/Vpn.java

@@ -25,6 +25,7 @@ import static android.net.NetworkCapabilities.NET_CAPABILITY_NOT_SUSPENDED;
 import static android.net.RouteInfo.RTN_THROW;
 import static android.net.RouteInfo.RTN_UNREACHABLE;
 
+import static com.android.internal.util.Preconditions.checkArgument;
 import static com.android.internal.util.Preconditions.checkNotNull;
 
 import android.Manifest;
@@ -2759,6 +2760,8 @@ public class Vpn {
 
         LegacyVpnRunner(VpnConfig config, String[] racoon, String[] mtpd, VpnProfile profile) {
             super(TAG);
+            checkArgument(racoon != null || mtpd != null, "Arguments to racoon and mtpd "
+                    + "must not both be null");
             mConfig = config;
             mDaemons = new String[] {"racoon", "mtpd"};
             // TODO: clear arguments from memory once launched
@@ -2915,15 +2918,6 @@ public class Vpn {
                 }
                 new File("/data/misc/vpn/abort").delete();
 
-                // Check if we need to restart any of the daemons.
-                boolean restart = false;
-                for (String[] arguments : mArguments) {
-                    restart = restart || (arguments != null);
-                }
-                if (!restart) {
-                    agentDisconnect();
-                    return;
-                }
                 updateState(DetailedState.CONNECTING, "execute");
 
                 // Start the daemon with arguments.