Added processing for a lost status to UpdateEngineClient.

chrome/browser/chromeos/login/screens/update_screen.cc

Index: chrome/browser/chromeos/login/screens/update_screen.cc
diff --git a/chrome/browser/chromeos/login/screens/update_screen.cc b/chrome/browser/chromeos/login/screens/update_screen.cc
index 86ef0d40fbd2d213207846153fd4a72508f12287..5c124516afc1949635e553bbdb178959de83dc3e 100644
--- a/chrome/browser/chromeos/login/screens/update_screen.cc
+++ b/chrome/browser/chromeos/login/screens/update_screen.cc
@@ -211,6 +211,9 @@ void UpdateScreen::UpdateStatusChanged(
       }
       // else no break
 
+    case UpdateEngineClient::UPDATE_STATUS_ATTEMPTING_ROLLBACK:
+      VLOG(1) << "Attempting rollback";
+      break;
     case UpdateEngineClient::UPDATE_STATUS_ERROR:
     case UpdateEngineClient::UPDATE_STATUS_REPORTING_ERROR_EVENT:
       ExitUpdate(REASON_UPDATE_ENDED);
@@ -329,6 +332,8 @@ void UpdateScreen::ExitUpdate(UpdateScreen::ExitReason reason) {
         UpdateEngineClient* update_engine_client =
             DBusThreadManager::Get()->GetUpdateEngineClient();
         switch (update_engine_client->GetLastStatus().status) {
+          case UpdateEngineClient::UPDATE_STATUS_ATTEMPTING_ROLLBACK:
+            break;
           case UpdateEngineClient::UPDATE_STATUS_UPDATE_AVAILABLE:
           case UpdateEngineClient::UPDATE_STATUS_UPDATED_NEED_REBOOT:
           case UpdateEngineClient::UPDATE_STATUS_DOWNLOADING: