Prevent overlays on Telephony settings screen.

Ensure only system overlays are allowed on telephony settings screens.

Flag: NONE Security fix
Bug: 335387175
Test: Manually launched activities to verify no overlays are possible.
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:46e18ac57da3ac50271fc2be5b20bd7799637eae)
Merged-In: I953667309753ff6fc966956e246512de97ad8638
Change-Id: I953667309753ff6fc966956e246512de97ad8638
diff --git a/src/com/android/phone/SimContacts.java b/src/com/android/phone/SimContacts.java
index d5f7840..fcbe4a0 100644
--- a/src/com/android/phone/SimContacts.java
+++ b/src/com/android/phone/SimContacts.java
@@ -232,6 +232,10 @@
     protected void onCreate(Bundle icicle) {
         super.onCreate(icicle);
 
+        getWindow().addSystemFlags(
+                android.view.WindowManager.LayoutParams
+                        .SYSTEM_FLAG_HIDE_NON_SYSTEM_OVERLAY_WINDOWS);
+
         Intent intent = getIntent();
         if (intent != null) {
             final String accountName = intent.getStringExtra("account_name");