Add support for managed profile configuration

- Add framework for reading and enforcing managed profile restrictions.
- Implement enforcement of search engine restriction.
- Add automated test for search engine restriction.

(cherry-picked from 4688934c52fa74e0c4280e4105e644f10221a8ed)

Change-Id: Ifb6018df584fedba42e86ab35d9bfa53b4d36ebe
diff --git a/res/values/strings.xml b/res/values/strings.xml
index a7d700d..cc63a70 100644
--- a/res/values/strings.xml
+++ b/res/values/strings.xml
@@ -1109,4 +1109,7 @@
     <string name="user_agent">User Agent</string>
     <string name="help">Help</string>
     <string name="feedback">Feedback</string>
+
+    <!-- Toast message displayed when user attempts to modify a setting disabled by the administrator -->
+    <string name="mdm_managed_alert">Managed by your administrator</string>
 </resources>