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

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

Index: ios/shared/chrome/browser/tabs/web_state_list_order_controller.mm
diff --git a/ios/shared/chrome/browser/tabs/web_state_list_order_controller.mm b/ios/shared/chrome/browser/tabs/web_state_list_order_controller.mm
new file mode 100644
index 0000000000000000000000000000000000000000..9bea16490053f29bedc743477dc603de5149cba6
--- /dev/null
+++ b/ios/shared/chrome/browser/tabs/web_state_list_order_controller.mm
@@ -0,0 +1,90 @@
+// 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_order_controller.h"
+
+#include <cstdint>
+
+#include "base/logging.h"
+#import "ios/shared/chrome/browser/tabs/web_state_list.h"
+#import "ios/shared/chrome/browser/tabs/web_state_opener.h"
+
+WebStateListOrderController::WebStateListOrderController(
+    WebStateList* web_state_list)
+    : web_state_list_(web_state_list) {
+  DCHECK(web_state_list_);
+}
+
+WebStateListOrderController::~WebStateListOrderController() = default;
+
+int WebStateListOrderController::DetermineInsertionIndex(
+    ui::PageTransition transition,
+    web::WebState* opener) const {
+  if (!opener)
+    return web_state_list_->count();
+
+  if (!PageTransitionCoreTypeIs(transition, ui::PAGE_TRANSITION_LINK))
+    return web_state_list_->count();
+
+  int opener_index = web_state_list_->GetIndexOfWebState(opener);
+  DCHECK_NE(WebStateList::kInvalidIndex, opener_index);
+
+  int list_child_index = web_state_list_->GetIndexOfLastWebStateOpenedBy(
+      opener, opener_index, true);
+
+  int reference_index = list_child_index != WebStateList::kInvalidIndex
+                            ? list_child_index
+                            : opener_index;
+
+  // Check for overflows (just a DCHECK as INT_MAX open WebState is unlikely).
+  DCHECK_LT(reference_index, INT_MAX);
+  return reference_index + 1;
+}
+
+int WebStateListOrderController::DetermineNewActiveIndex(
+    int removing_index) const {
+  DCHECK(web_state_list_->ContainsIndex(removing_index));
+  // First see if the index being removed has any "child" WebState. If it does,
+  // select the first WebState in that child group, not the next in the removed
+  // index group.
+  int index = web_state_list_->GetIndexOfNextWebStateOpenedBy(
+      web_state_list_->GetWebStateAt(removing_index), removing_index, false);
+
+  if (index != WebStateList::kInvalidIndex)
+    return GetValidIndex(index, removing_index);
+
+  WebStateOpener opener =
+      web_state_list_->GetOpenerOfWebStateAt(removing_index);
+  if (opener.opener) {
+    // If the WebState was in a group, shift selection to the next WebState in
+    // the group.
+    int index = web_state_list_->GetIndexOfNextWebStateOpenedBy(
+        opener.opener, removing_index, false);
+
+    if (index != WebStateList::kInvalidIndex)
+      return GetValidIndex(index, removing_index);
+
+    // If there is no subsequent group member, just fall back to opener itself.
+    index = web_state_list_->GetIndexOfWebState(opener.opener);
+    return GetValidIndex(index, removing_index);
+  }
+
+  // If this is the last WebState in the WebStateList, clear the selection.
+  if (web_state_list_->count() == 1)
+    return WebStateList::kInvalidIndex;
+
+  // No opener, fall through to the default handler, i.e. returning the previous
+  // WebState if the removed one is the last, otherwise returning the next one.
+  if (removing_index >= web_state_list_->count() - 1)
+    return removing_index - 1;
+
+  return removing_index;
+}
+
+int WebStateListOrderController::GetValidIndex(int index,
+                                               int removing_index) const {
+  if (removing_index < index)
+    return std::min(0, index - 1);
+  return index;
+}