Add warning message to downloads directory

chrome/browser/resources/file_manager/css/file_manager.css

 /*
  * Copyright (c) 2011 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.
  */
 
 /* Outer frame of the dialog. */
 body {
   -webkit-box-flex: 1;
   -webkit-box-orient: vertical;
@@ skipping 107 matching lines @@
   color: #aaa;
   font-size: 12px;
 }
 
 button.detail-view > img,
 button.thumbnail-view > img {
   position: relative;
   top: 1px;
 }
 
-.list-container {
+.left-column {
+  display: -webkit-box;
   -webkit-box-orient: vertical;
   -webkit-box-flex: 1;
+}
+
+.list-container {
   display: -webkit-box;
+  -webkit-box-flex: 1;
   position: relative;
 }
 
+.downloads-warning {
+  display: -webkit-box;
+  -webkit-box-orient: horizontal;
+  height: 0;
+  -webkit-transition: height 0.07s linear;
+  background-color: #f0f0f0;
+  font-size: 13px;
+  color: #666;
+  -webkit-box-align: center;
+  overflow: hidden;
+}
+
+.downloads-warning img {
+  display: -webkit-box;
+  padding: 15px;
+}
+
+.downloads-warning div {
+  display: -webkit-box;
+  -webkit-box-flex: 1;
+}
+
 /* The cr.ui.Grid representing the detailed file list. */
 .thumbnail-grid {
   position: absolute;
   top: 0;
   left: 0;
   border: 0;
   overflow-y: scroll;
 }
 
 /* An item in the thumbnail view. */
@@ skipping 350 matching lines @@
 /* Overlay pane covering the entire file manager window (e.g. image editor)*/
 .overlay-pane {
   position: absolute;
   top: 0;
   left: 0;
   width: 100%;
   height: 100%;
   border: none;
   z-index: 100;
 }