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

ios/shared/chrome/browser/tabs/web_state_list_order_controller.h

Index: ios/shared/chrome/browser/tabs/web_state_list_order_controller.h
diff --git a/ios/shared/chrome/browser/tabs/web_state_list_order_controller.h b/ios/shared/chrome/browser/tabs/web_state_list_order_controller.h
new file mode 100644
index 0000000000000000000000000000000000000000..5422c8ffa2d02e66f3c932b72537f2e5404ac284
--- /dev/null
+++ b/ios/shared/chrome/browser/tabs/web_state_list_order_controller.h
@@ -0,0 +1,43 @@
+// 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_SHARED_CHROME_BROWSER_TABS_WEB_STATE_LIST_ORDER_CONTROLLER_H_
+#define IOS_SHARED_CHROME_BROWSER_TABS_WEB_STATE_LIST_ORDER_CONTROLLER_H_
+
+#include "base/macros.h"
+#include "ui/base/page_transition_types.h"
+
+class WebStateList;
+
+namespace web {
+class WebState;
+}
+
+// WebStateListOrderController allows different types of ordering and
+// selection heuristics to be plugged into WebStateList.
+class WebStateListOrderController {
+ public:
+  explicit WebStateListOrderController(WebStateList* web_state_list);
+  ~WebStateListOrderController();
+
+  // Determines where to place a newly opened WebState by using the supplied
+  // transition, opener and background flag.
+  int DetermineInsertionIndex(ui::PageTransition transition,
+                              web::WebState* opener) const;
+
+  // Determines where to shift the active index after a WebState is closed.
+  int DetermineNewActiveIndex(int removing_index) const;
+
+ private:
+  // Returns a valid index to be selected after the WebState at |removing_index|
+  // is detached, adjusting |index| to reflect that |removing_index| is going
+  // away.
+  int GetValidIndex(int index, int removing_index) const;
+
+  WebStateList* web_state_list_;
+
+  DISALLOW_COPY_AND_ASSIGN(WebStateListOrderController);
+};
+
+#endif  // IOS_SHARED_CHROME_BROWSER_TABS_WEB_STATE_LIST_ORDER_CONTROLLER_H_