AU: Announce the update engine status on startup.

This is to ensure that the system is in a consistent state in case update-engine
crashes.

BUG=chromium-os:15069
TEST=press "Check for update" in Chrome, restart update-engine while downloading
an update, see the status go back to 'up to date' (rather than get stuck in
'Downloading')

Change-Id: I1e89502a9fa134ec3a81e50a9036ce20b46eb9b0
Reviewed-on: http://gerrit.chromium.org/gerrit/1144
Tested-by: Darin Petkov <petkov@chromium.org>
Reviewed-by: Andrew de los Reyes <adlr@chromium.org>
diff --git a/update_attempter.h b/update_attempter.h
index 3bbd2ef..f4b82ff 100644
--- a/update_attempter.h
+++ b/update_attempter.h
@@ -126,6 +126,9 @@
   void SetDownloadStatus(bool active);
   void BytesReceived(uint64_t bytes_received, uint64_t total);
 
+  // Broadcasts the current status over D-Bus.
+  void BroadcastStatus();
+
  private:
   friend class UpdateAttempterTest;
   FRIEND_TEST(UpdateAttempterTest, ActionCompletedDownloadTest);