[Navigation Experiment] Add WKBasedNavigationManagerImpl.

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 WebViewNavigationProxy;
 
 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;
+  WebViewNavigationProxy* GetWebViewNavigationProxy() const override;
 };
 
 }  // namespace web
 
 #endif  // IOS_WEB_TEST_FAKES_TEST_NAVIGATION_MANAGER_DELEGATE_H_