It is time.

ui/base/models/combobox_model.cc

Index: ui/base/models/combobox_model.cc
diff --git a/ui/base/models/combobox_model.cc b/ui/base/models/combobox_model.cc
deleted file mode 100644
index c6913da55e5f3b370a2330fe0e5de3573e1d54fe..0000000000000000000000000000000000000000
--- a/ui/base/models/combobox_model.cc
+++ /dev/null
@@ -1,21 +0,0 @@
-// Copyright (c) 2012 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.
-
-#include "ui/base/models/combobox_model.h"
-
-namespace ui {
-
-bool ComboboxModel::IsItemSeparatorAt(int index) {
-  return false;
-}
-
-int ComboboxModel::GetDefaultIndex() const {
-  return 0;
-}
-
-bool ComboboxModel::IsItemEnabledAt(int index) const {
-  return true;
-}
-
-}  // namespace ui