Fix build when ENABLE_MANAGED_USERS is not defined

chrome/browser/ui/webui/downloads_ui_supervised_browsertest.cc

Index: chrome/browser/ui/webui/downloads_ui_supervised_browsertest.cc
diff --git a/chrome/browser/ui/webui/downloads_ui_supervised_browsertest.cc b/chrome/browser/ui/webui/downloads_ui_supervised_browsertest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..52d7f2753fb532a1f201feaf8f4ceb746da4045b
--- /dev/null
+++ b/chrome/browser/ui/webui/downloads_ui_supervised_browsertest.cc
@@ -0,0 +1,15 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "chrome/browser/ui/webui/downloads_ui_supervised_browsertest.h"
+
+#include "base/command_line.h"
+#include "chrome/browser/ui/browser.h"
+#include "chrome/common/chrome_switches.h"
+#include "content/public/test/test_utils.h"
+
+void DownloadsWebUIForSupervisedUsersTest::SetUpCommandLine(
+    CommandLine* command_line) {
+  command_line->AppendSwitchASCII(switches::kSupervisedUserId, "asdf");
+}