Revert of [ios] Move WebStateList to ios/chrome/browser/web_state_list.

ios/chrome/browser/web_state_list/web_state_opener.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_CHROME_BROWSER_WEB_STATE_LIST_WEB_STATE_OPENER_H_
-#define IOS_CHROME_BROWSER_WEB_STATE_LIST_WEB_STATE_OPENER_H_
-
-namespace web {
-class WebState;
-}
-
-// Represents the opener of a WebState.
-struct WebStateOpener {
-  // WebState responsible for the creation of the new WebState. May be null if
-  // the WebState has no opener.
-  web::WebState* opener;
-
-  // Recorded value of the |opener| last committed navigation index when the
-  // WebState was open. Value is undefined if |opener| is null.
-  int navigation_index;
-
-  // Creates WebStateOpener initialising the members from |opener| (the
-  // |navigation_index| will be initialised from |opener|'s navigation
-  // manager if |opener| is not null).
-  explicit WebStateOpener(web::WebState* opener);
-
-  // Creates WebStateOpener initialising the members from the parameters.
-  WebStateOpener(web::WebState* opener, int navigation_index);
-
-  // Forbids default construction.
-  WebStateOpener() = delete;
-};
-
-#endif  // IOS_CHROME_BROWSER_WEB_STATE_LIST_WEB_STATE_OPENER_H_