Fix failing NavigationManagerUtil test that wasn't being run.

ios/web/test/fakes/test_navigation_manager_delegate.h

+// Copyright 2017 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_TEST_FAKES_TEST_NAVIGATION_MANAGER_DELEGATE_H_
+#define IOS_WEB_TEST_FAKES_TEST_NAVIGATION_MANAGER_DELEGATE_H_
+
+#import "ios/web/navigation/navigation_manager_delegate.h"
+
+namespace web {
+
+class TestNavigationManagerDelegate : public NavigationManagerDelegate {
+ public:
+  void GoToIndex(int index) override;
+  void LoadURLWithParams(const NavigationManager::WebLoadParams&) override;
+  void Reload() override;
+  void OnNavigationItemsPruned(size_t pruned_item_count) override;
+  void OnNavigationItemChanged() override;
+  void OnNavigationItemCommitted(
+      const LoadCommittedDetails& load_details) override;
+  WebState* GetWebState() override;
+};
+
+}  // namespace web
+
+#endif  // IOS_WEB_TEST_FAKES_TEST_NAVIGATION_MANAGER_DELEGATE_H_