Remove some platform specific stuff from views.

ui/file_manager/file_manager/foreground/css/combobutton.css

Index: ui/file_manager/file_manager/foreground/css/combobutton.css
diff --git a/ui/file_manager/file_manager/foreground/css/combobutton.css b/ui/file_manager/file_manager/foreground/css/combobutton.css
deleted file mode 100644
index a5fef650091975e5320f9fdd3a652baaf5697e4c..0000000000000000000000000000000000000000
--- a/ui/file_manager/file_manager/foreground/css/combobutton.css
+++ /dev/null
@@ -1,48 +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. */
-
-.buttonbar button.combobutton {
-  align-items: stretch;
-  display: flex;
-}
-
-.buttonbar .combobutton > .action {
-  -webkit-padding-start: 21px;
-  background-position: left center;
-  background-repeat: no-repeat;
-  background-size: 16px 16px;
-}
-
-html[dir='rtl'] .buttonbar .combobutton > .action {
-  background-position: right center;
-}
-
-.buttonbar .combobutton > .trigger {
-  -webkit-border-start: solid 1px #dcdcdc;
-  -webkit-margin-end: -8px;
-  -webkit-margin-start: 8px;
-  width: 22px;
-}
-
-/* This pseudo element expands clickable area of the .trigger */
-.buttonbar .combobutton > .trigger::before {
-  content: '';
-  display: block;
-  height: 31px;
-  position: absolute;
-  top: -5px;
-  width: 30px;
-}
-
-.buttonbar .combobutton:not([multiple]) > .trigger {
-  display: none;
-}
-
-.buttonbar .combobutton > div > span.disclosureindicator {
-  -webkit-transform: rotate(90deg);
-}
-
-.buttonbar .combobutton[hidden] {
-  display: none;
-}