Added the AutoEnrollmentClient and unit tests for it.

chrome/browser/automation/automation_provider_observers.cc

Index: chrome/browser/automation/automation_provider_observers.cc
diff --git a/chrome/browser/automation/automation_provider_observers.cc b/chrome/browser/automation/automation_provider_observers.cc
index 670d01e09e221292b9301836d6f92958a3a74e61..7ea7e233be48a2c9455f21fce62ab97d3b3ba4ba 100644
--- a/chrome/browser/automation/automation_provider_observers.cc
+++ b/chrome/browser/automation/automation_provider_observers.cc
@@ -3058,6 +3058,8 @@ void PolicyUpdatesObserver::Reply() {
     AutomationJSONReply(
         automation_, reply_message_.release()).SendSuccess(NULL);
   }
+  // Reply() is only called from MaybeReply(), which makes the callback own
+  // |this|; so |this| will be deleted once this method returns.
 }
 
 // static