Add support to update_engine to poke Omaha after an update has been applied
successfully and is awaiting reboot to help ensure the number of actives
remains accurate.

BUG=chromium-os:12026
TEST=Manual test, unit tests

Change-Id: Ie3397264b0b34e8d423fb9748970f7d330122180

Review URL: http://codereview.chromium.org/6836025
diff --git a/omaha_request_action.h b/omaha_request_action.h
index 8749546..fd7f548 100644
--- a/omaha_request_action.h
+++ b/omaha_request_action.h
@@ -129,7 +129,8 @@
   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 @@
   // 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_;