Allow factory reset in carrier demo mode

Bug: 34341567
Test: manual - in carrier demo mode, go to Settings > Backup and
Reset > Factory data reset > Reset phone > Erase everything and
this entire path is viewable.

Change-Id: Ia5491765241adad97ecdb0a5bfd86a8371b8e4fe

src/com/android/settings/Utils.java

@@ -1245,4 +1245,13 @@ public final class Utils extends com.android.settingslib.Utils {
         }
     }
 
+    public static boolean isCarrierDemoUser(Context context) {
+        final String carrierDemoModeSetting =
+                context.getString(com.android.internal.R.string.config_carrierDemoModeSetting);
+        return UserManager.isDeviceInDemoMode(context)
+                && getUserManager(context).isDemoUser()
+                && !TextUtils.isEmpty(carrierDemoModeSetting)
+                && (Settings.Secure.getInt(context.getContentResolver(),
+                        carrierDemoModeSetting, 0) == 1);
+    }
 }