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

update_attempter.h

Index: update_attempter.h
diff --git a/update_attempter.h b/update_attempter.h
index e41cab920c058a485e54cec53a086cbf6ecfe541..c4235e971de2aef1ccf72d0baf60fbade0e3f0cc 100644
--- a/update_attempter.h
+++ b/update_attempter.h
@@ -123,6 +123,7 @@ class UpdateAttempter : public ActionProcessorDelegate,
   FRIEND_TEST(UpdateAttempterTest, ScheduleErrorEventActionNoEventTest);
   FRIEND_TEST(UpdateAttempterTest, ScheduleErrorEventActionTest);
   FRIEND_TEST(UpdateAttempterTest, UpdateTest);
+  FRIEND_TEST(UpdateAttempterTest, PingOmahaTest);
 
   // Sets the status to the given status and notifies a status update
   // over dbus.
@@ -175,6 +176,13 @@ class UpdateAttempter : public ActionProcessorDelegate,
         reinterpret_cast<ProxyResolver*>(&direct_proxy_resolver_);
   }
 
+  // Sends a ping to Omaha.
+  // This is used after an update has been applied and we're waiting for the
+  // user to reboot.  This ping helps keep the number of actives count
+  // accurate in case a user takes a long time to reboot the device after an
+  // update has been applied.
+  void PingOmaha();
+
   // Last status notification timestamp used for throttling. Use monotonic
   // TimeTicks to ensure that notifications are sent even if the system clock is
   // set back in the middle of an update.