Handle null intent in StkAppService.

Bug 2151421. The onStart() may be passed a null intent if a service is restarted and it need handle the null intent for now.
diff --git a/src/com/android/stk/StkAppService.java b/src/com/android/stk/StkAppService.java
index d13be1d..7831503 100644
--- a/src/com/android/stk/StkAppService.java
+++ b/src/com/android/stk/StkAppService.java
@@ -161,7 +161,14 @@
     public void onStart(Intent intent, int startId) {
         waitForLooper();
 
+        // onStart() method can be passed a null intent
+        // TODO: replace onStart() with onStartCommand()
+        if (intent == null) {
+            return;
+        }
+
         Bundle args = intent.getExtras();
+
         if (args == null) {
             return;
         }