FragmentReceiveResultTest: Add FLAG_IMMUTABLE to PIs

Change-Id: I4718792c0f8b088968189cad32be433e02f50876
Fixes: 176910528
Test: this
diff --git a/tests/app/src/android/app/cts/FragmentReceiveResultTest.java b/tests/app/src/android/app/cts/FragmentReceiveResultTest.java
index 915e09d..ca4ae73 100644
--- a/tests/app/src/android/app/cts/FragmentReceiveResultTest.java
+++ b/tests/app/src/android/app/cts/FragmentReceiveResultTest.java
@@ -146,7 +146,7 @@
                 intent.putExtra(FragmentResultActivity.EXTRA_RESULT_CONTENT, content);
 
                 PendingIntent pendingIntent = PendingIntent.getActivity(mActivity,
-                        requestCode, intent, 0);
+                        requestCode, intent, PendingIntent.FLAG_IMMUTABLE);
 
                 try {
                     mFragment.startIntentSenderForResult(pendingIntent.getIntentSender(),