[Navigation Experiment] Add WKBasedNavigationManagerImpl.

ios/web/test/fakes/test_navigation_manager_delegate.mm

 // 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.
 
 #import "ios/web/test/fakes/test_navigation_manager_delegate.h"
+#import "ios/web/web_state/ui/web_view_navigation_proxy.h"
 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
 #error "This file requires ARC support."
 #endif
 
 namespace web {
 
 void TestNavigationManagerDelegate::GoToIndex(int index) {}
 void TestNavigationManagerDelegate::LoadURLWithParams(
     const NavigationManager::WebLoadParams&) {}
 void TestNavigationManagerDelegate::Reload() {}
 void TestNavigationManagerDelegate::OnNavigationItemsPruned(
     size_t pruned_item_count) {}
 void TestNavigationManagerDelegate::OnNavigationItemChanged() {}
 void TestNavigationManagerDelegate::OnNavigationItemCommitted(
     const LoadCommittedDetails& load_details) {}
 WebState* TestNavigationManagerDelegate::GetWebState() {
   return nullptr;
 }
+id<WebViewNavigationProxy>
+TestNavigationManagerDelegate::GetWebViewNavigationProxy() const {
+  return nil;
+}
 
 }  // namespace web