Mark these token strings as untranslatable.

Change-Id: I7ec6ca85a12cb705bc7c934509f1da547d6c4ed1
diff --git a/res/values/strings.xml b/res/values/strings.xml
index 3e9a7be..977fddd 100644
--- a/res/values/strings.xml
+++ b/res/values/strings.xml
@@ -318,7 +318,7 @@
         <item>On demand</item>
         <item>Off</item>
     </string-array>
-    <string-array name="pref_content_plugins_values">
+    <string-array name="pref_content_plugins_values" translatable="false">
         <item>ON</item>
         <item>ON_DEMAND</item>
         <item>OFF</item>