Converted CRWSessionController to use NavigationItems.

ios/web/navigation/navigation_item_impl_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/web/navigation/navigation_item_impl_list.h"
+
+#import "ios/web/navigation/navigation_item_impl.h"
+
+namespace web {
+
+ScopedNavigationItemImplList CreateScopedNavigationItemImplList(
+    ScopedNavigationItemList scoped_item_list) {
+  ScopedNavigationItemImplList list;
+  for (size_t index = 0; index < scoped_item_list.size(); ++index) {
+    std::unique_ptr<NavigationItemImpl> scoped_item_impl(
+        static_cast<NavigationItemImpl*>(scoped_item_list[index].release()));
+    list.push_back(std::move(scoped_item_impl));
+  }
+  return list;
+}
+
+}  // namespace web