Add WebStateListOrderController to control WebState insertion.

ios/shared/chrome/browser/tabs/web_state_list.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/shared/chrome/browser/tabs/web_state_list.h"
 
 #include <utility>
 
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
 #import "ios/shared/chrome/browser/tabs/web_state_list_observer.h"
+#import "ios/shared/chrome/browser/tabs/web_state_list_order_controller.h"
 #import "ios/web/public/navigation_manager.h"
 #import "ios/web/public/web_state/web_state.h"
 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
 #error "This file requires ARC support."
 #endif
 
 // Wrapper around a WebState stored in a WebStateList. May own the WebState
 // dependending on the WebStateList ownership setting (should always be true
 // once ownership of Tab is sane, see http://crbug.com/546222 for progress).
@@ skipping 66 matching lines @@
   if (opener_ != opener)
     return false;
 
   if (!use_group)
     return true;
 
   return opener_last_committed_index_ == opener_navigation_index;
 }
 
 WebStateList::WebStateList(WebStateOwnership ownership)
-    : web_state_ownership_(ownership) {}
+    : web_state_ownership_(ownership),
+      order_controller_(base::MakeUnique<WebStateListOrderController>(this)) {}
 
 WebStateList::~WebStateList() = default;
 
 bool WebStateList::ContainsIndex(int index) const {
   return 0 <= index && index < count();
 }
 
 web::WebState* WebStateList::GetWebStateAt(int index) const {
   DCHECK(ContainsIndex(index));
   return web_state_wrappers_[index]->web_state();
@@ skipping 39 matching lines @@
       base::MakeUnique<WebStateWrapper>(web_state,
                                         web_state_ownership_ == WebStateOwned));
 
   if (opener)
     SetOpenerOfWebStateAt(index, opener);
 
   for (auto& observer : observers_)
     observer.WebStateInsertedAt(this, web_state, index);
 }
 
+void WebStateList::AppendWebState(ui::PageTransition transition,
+                                  web::WebState* web_state,
+                                  web::WebState* opener) {
+  int index = order_controller_->DetermineInsertionIndex(transition, opener);
+  if (index < 0 || count() < index)
+    index = count();
+
+  InsertWebState(index, web_state, opener);
+}
+
 void WebStateList::MoveWebStateAt(int from_index, int to_index) {
   DCHECK(ContainsIndex(from_index));
   DCHECK(ContainsIndex(to_index));
   if (from_index == to_index)
     return;
 
   std::unique_ptr<WebStateWrapper> web_state_wrapper =
       std::move(web_state_wrappers_[from_index]);
   web::WebState* web_state = web_state_wrapper->web_state();
   web_state_wrappers_.erase(web_state_wrappers_.begin() + from_index);
@@ skipping 69 matching lines @@
     } else if (found_index != kInvalidIndex) {
       return found_index;
     }
   }
 
   return found_index;
 }
 
 // static
 const int WebStateList::kInvalidIndex;