arc: ARC loading progress should not be shown when started from OOBE.

chrome/browser/chromeos/arc/arc_support_host.h

Index: chrome/browser/chromeos/arc/arc_support_host.h
diff --git a/chrome/browser/chromeos/arc/arc_support_host.h b/chrome/browser/chromeos/arc/arc_support_host.h
index 9a33c41a17166439747d8b4cd5e7df56e72940a2..399815d0f2e2d18ab99644dc37e8a3408903108f 100644
--- a/chrome/browser/chromeos/arc/arc_support_host.h
+++ b/chrome/browser/chromeos/arc/arc_support_host.h
@@ -125,6 +125,9 @@ class ArcSupportHost : public arc::ArcSupportMessageHost::Observer,
   // TODO(hidehiko): Remove this exposure.
   UIPage ui_page() const { return ui_page_; }
 
+  // Returns true if message host is currently attached which means UI is shown.
+  bool has_message_host() const { return message_host_; }
+
   void SetRequestOpenAppCallbackForTesting(
       const RequestOpenAppCallback& callback);