[Navigation Experiment] Add WKBasedNavigationManagerImpl.

ios/web/navigation/web_view_navigation_proxy.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_NAVIGATION_WEB_VIEW_NAVIGATION_PROXY_H_
+#define IOS_WEB_NAVIGATION_WEB_VIEW_NAVIGATION_PROXY_H_
+
+@class NSArray;
+@class WKBackForwardListItem;
+
+namespace web {
+
+// Interface to expose navigation related functionality on WKWebView.
+class WebViewNavigationProxy {
+ public:
+  virtual ~WebViewNavigationProxy() {}
+
+  virtual bool HasWebView() const = 0;
+
+  virtual bool CanGoBack() const = 0;
+  virtual bool CanGoForward() const = 0;
+  virtual void GoBack() const = 0;
+  virtual void GoForward() const = 0;
+  virtual void GoToBackForwardListItem(WKBackForwardListItem* item) const = 0;
+
+  virtual WKBackForwardListItem* GetCurrentItem() const = 0;
+  virtual NSArray<WKBackForwardListItem*>* GetBackList() const = 0;
+  virtual NSArray<WKBackForwardListItem*>* GetForwardList() const = 0;
+  virtual WKBackForwardListItem* GetItemAtOffset(int offset) const = 0;
+};
+
+}  // namespace web
+
+#endif  // IOS_WEB_NAVIGATION_WEB_VIEW_NAVIGATION_PROXY_H_