MD downloads: implement real incognito marker courtesy of bettes@

chrome/browser/resources/md_downloads/item.css

 /* Copyright 2015 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. */
 
 :host {
   @apply(--downloads-shared-style);
   display: flex;
   margin: 32px 0;
 }
 
@@ skipping 120 matching lines @@
   --paper-progress-active-color: rgb(54, 126, 237);
   --paper-progress-container-color: rgb(223, 222, 223);
   width: auto;
 }
 
 /* TODO(dbeam): open up a CSS mixin instead in Polymer. */
 #progress /deep/ #progressContainer {
   border-radius: 2px;
 }
 
-#incognito {
-  -webkit-margin-end: 0;
-  -webkit-margin-start: 16px;
-  /* This image is 128x128 so it'll work fine in 2x. */
-  content: url(../../../../ui/webui/resources/images/incognito_icon.png);
-  width: 48px;
-}
-
 #remove-wrapper {
   align-self: flex-start;
   margin: 0;
 }
 
 #remove {
   --paper-icon-button: {
     height: 16px;
     width: 16px;
   };
   --iron-icon-height: 16px;
   --iron-icon-width: 16px;
 }
 
+#incognito {
+  bottom: 16px;
+  content: -webkit-image-set(url(1x/incognito_marker.png) 1x,
+                             url(2x/incognito_marker.png) 2x);
+  position: absolute;
+  right: 10px;
+}
+
 @media not all and (max-width: 1024px) {
   /* Only show date separators in wide mode. */
   :host(:not(:first-of-type):not([hide-date])) :-webkit-any(#content-wrapper,
                                                             #since) {
     border-top: 1px solid rgba(0, 0, 0, .2);  /* TODO(dbeam): real color. */
     padding-top: 32px;
   }
 
   #date-container > * {
     -webkit-margin-start: 24px;
@@ skipping 14 matching lines @@
   #content {
     margin: 0 auto;
   }
 
   #date-container {
     flex: none !important;
     margin: 0 auto 32px;
     width: var(--downloads-item-width);
   }
 }