Remove some platform specific stuff from views.

ui/file_manager/file_manager/foreground/css/tree.css

Index: ui/file_manager/file_manager/foreground/css/tree.css
diff --git a/ui/file_manager/file_manager/foreground/css/tree.css b/ui/file_manager/file_manager/foreground/css/tree.css
deleted file mode 100644
index e151977f7549f93e3796943eba55bb8e3aff8276..0000000000000000000000000000000000000000
--- a/ui/file_manager/file_manager/foreground/css/tree.css
+++ /dev/null
@@ -1,83 +0,0 @@
-/* Copyright 2013 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. */
-
-/* Derived from /ui/webui/resources/css/table.css. */
-
-tree {
-  display: block;
-  outline: none;
-  overflow: auto;
-}
-
-.tree-item > .tree-row {
-  -webkit-user-select: none;
-  cursor: default;
-  position: relative;
-  white-space: nowrap;
-}
-
-.expand-icon {
-  -webkit-transform: rotate(-90deg);
-  -webkit-transition: all 150ms;
-  background-image: -webkit-canvas(tree-triangle);
-  background-position: 50% 50%;
-  background-repeat: no-repeat;
-  background-size: 8px 5px;
-  display: inline-block;
-  height: 16px;
-  position: relative;
-  vertical-align: top;
-}
-
-html[dir=rtl] .expand-icon {
-  -webkit-transform: rotate(90deg);
-}
-
-.tree-item[expanded] > .tree-row > .expand-icon {
-  -webkit-transform: rotate(0);
-  background-image: -webkit-canvas(tree-triangle);
-}
-
-.tree-row .expand-icon {
-  visibility: hidden;
-}
-
-.tree-row[may-have-children] .expand-icon {
-  visibility: visible;
-}
-
-.tree-row[has-children=false] .expand-icon {
-  visibility: hidden;
-}
-
-.tree-row[selected] {
-  z-index: 2;
-}
-
-.tree-children[expanded] {
-  display: block;
-}
-
-.tree-children {
-  display: none;
-}
-
-.tree-item > .tree-row > * {
-  display: inline-block;
-}
-
-.tree-label {
-  white-space: pre;
-}
-
-/* We need to ensure that even empty labels take up space */
-.tree-label:empty::after {
-  content: ' ';
-  white-space: pre;
-}
-
-.tree-rename > .tree-row > .tree-label {
-  -webkit-user-modify: read-write-plaintext-only;
-  -webkit-user-select: auto;
-}