Set the correct flags for brightness dialog to show on all users

Earlier fix was writing to the wrong flags.

Bug: 7393822
Change-Id: Ifd51fb30de00be6de381980a05f2769c4283b515

Author: Amith Yamasani

packages/SystemUI/src/com/android/systemui/statusbar/phone/QuickSettings.java

@@ -771,8 +771,8 @@ public void onDismiss(DialogInterface dialog) {
             });
 
             mBrightnessDialog.getWindow().setType(WindowManager.LayoutParams.TYPE_SYSTEM_ALERT);
-            mBrightnessDialog.getWindow().addFlags(
-                    WindowManager.LayoutParams.PRIVATE_FLAG_SHOW_FOR_ALL_USERS);
+            mBrightnessDialog.getWindow().getAttributes().privateFlags |=
+                    WindowManager.LayoutParams.PRIVATE_FLAG_SHOW_FOR_ALL_USERS;
             mBrightnessDialog.getWindow().clearFlags(WindowManager.LayoutParams.FLAG_DIM_BEHIND);
         }
         if (!mBrightnessDialog.isShowing()) {