Stop a daemon before starting it

in case the daemon is not cleaned up in last session.

packages/VpnServices/src/com/android/server/vpn/AndroidServiceProxy.java

@@ -106,6 +106,13 @@ public class AndroidServiceProxy extends ProcessProxy {
     @Override
     protected void performTask() throws IOException {
         String svc = mServiceName;
+        Log.d(mTag, "-----  Stop the daemon just in case: " + mServiceName);
+        SystemProperties.set(SVC_STOP_CMD, mServiceName);
+        if (!blockUntil(SVC_STATE_STOPPED, 5)) {
+            throw new IOException("cannot start service anew: " + svc
+                    + ", it is still running");
+        }
+
         Log.d(mTag, "+++++  Start: " + svc);
         SystemProperties.set(SVC_START_CMD, svc);
 

packages/VpnServices/src/com/android/server/vpn/VpnServiceBinder.java

@@ -57,6 +57,7 @@ public class VpnServiceBinder extends Service {
     public void onStart (Intent intent, int startId) {
         super.onStart(intent, startId);
         setForeground(true);
+        android.util.Log.d("VpnServiceBinder", "becomes a foreground service");
     }
 
     public IBinder onBind(Intent intent) {