Add support to update_engine to poke Omaha after an update has been applied

omaha_request_action.h

Index: omaha_request_action.h
diff --git a/omaha_request_action.h b/omaha_request_action.h
index 8749546b00465aaf94e7a3f9ae2973099f43e56e..fd7f548decd45959762c37b017c5c15752a6847d 100644
--- a/omaha_request_action.h
+++ b/omaha_request_action.h
@@ -129,7 +129,8 @@ class OmahaRequestAction : public Action<OmahaRequestAction>,
   OmahaRequestAction(PrefsInterface* prefs,
                      const OmahaRequestParams& params,
                      OmahaEvent* event,
-                     HttpFetcher* http_fetcher);
+                     HttpFetcher* http_fetcher,
+                     bool ping_only);
   virtual ~OmahaRequestAction();
   typedef ActionTraits<OmahaRequestAction>::InputObjectType InputObjectType;
   typedef ActionTraits<OmahaRequestAction>::OutputObjectType OutputObjectType;
@@ -174,6 +175,9 @@ class OmahaRequestAction : public Action<OmahaRequestAction>,
   // pointer to the HttpFetcher that does the http work
   scoped_ptr<HttpFetcher> http_fetcher_;
 
+  // If true, only include the <ping> element in the request.
+  bool ping_only_;
+
   // Stores the response from the omaha server
   std::vector<char> response_buffer_;