arc: Restore UMA statistics for failures in LSO flow.

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..24ab4221d3370a255113e8f702600a5ec856a0e9 100644
--- a/chrome/browser/chromeos/arc/arc_support_host.h
+++ b/chrome/browser/chromeos/arc/arc_support_host.h
@@ -59,6 +59,9 @@ class ArcSupportHost : public arc::ArcSupportMessageHost::Observer,
     // Called when LSO auth token fetch is successfully completed.
     virtual void OnAuthSucceeded(const std::string& auth_code) {}
 
+    // Called when LSO auth token fetch has failed.
+    virtual void OnAuthFailed() {}
+
     // Called when "RETRY" button on the error page is clicked.
     virtual void OnRetryClicked() {}