Fix 2579224: Add a separate timeout for lockscreen vs display

This change adds a second timeout to the SecuritySettings page
separate from the standard display timeout.

Change-Id: I033a3578d876148bd723dee5d1a2531be5d6b51d
diff --git a/res/xml/security_settings_pattern.xml b/res/xml/security_settings_pattern.xml
index 095828a..200c260 100644
--- a/res/xml/security_settings_pattern.xml
+++ b/res/xml/security_settings_pattern.xml
@@ -20,6 +20,14 @@
         android:key="security_category"
         android:title="@string/lock_settings_title">
 
+        <ListPreference
+            android:key="lock_after_timeout"
+            android:title="@string/lock_after_timeout"
+            android:summary="@string/lock_after_timeout_summary"
+            android:entries="@array/lock_after_timeout_entries"
+            android:entryValues="@array/lock_after_timeout_values" 
+            android:persistent="false"/>
+            
         <PreferenceScreen
             android:key="unlock_set_or_change"
             android:title="@string/unlock_set_unlock_launch_picker_change_title"