cros: Terminate if merge session fails for online sign-in

google_apis/gaia/fake_gaia.cc

Index: google_apis/gaia/fake_gaia.cc
diff --git a/google_apis/gaia/fake_gaia.cc b/google_apis/gaia/fake_gaia.cc
index 3c91f25c685597809b00d8baa394101a0f5796ec..c74fbf93b4aaca959b6edd9cb22ad5e595948b4b 100644
--- a/google_apis/gaia/fake_gaia.cc
+++ b/google_apis/gaia/fake_gaia.cc
@@ -525,6 +525,7 @@ void FakeGaia::HandleOAuthLogin(const HttpRequest& request,
   http_response->set_code(net::HTTP_UNAUTHORIZED);
   if (merge_session_params_.gaia_uber_token.empty()) {
     http_response->set_code(net::HTTP_FORBIDDEN);
+    http_response->set_content("Error=BadAuthentication");
     return;
   }