Web shell test to go back and forward.

ios/web/shell/test/navigation_test_util.h

+// Copyright 2016 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.
+
+#ifndef IOS_WEB_SHELL_TEST_NAVIGATION_TEST_UTIL_H_
+#define IOS_WEB_SHELL_TEST_NAVIGATION_TEST_UTIL_H_
+
+#include "url/gurl.h"
+
+namespace web {
+namespace navigation_test_util {
+
+// Loads |url| in current webState with transition of type
+// ui::PAGE_TRANSITION_TYPED.
+void LoadUrl(GURL url);
+
+}  // namespace navigation_test_util
+}  // namespace web
+
+#endif  // IOS_WEB_SHELL_TEST_NAVIGATION_TEST_UTIL_H_