Inconsistent use of [x] close panel icon. Code changes.

ui/webui/resources/css/bubble.css

 /* 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. */
 
 .bubble {
   position: absolute;
   white-space: normal;
   /* Height is dynamic, width fixed. */
   width: 300px;
   z-index: 9999;
@@ skipping 24 matching lines @@
   z-index: 4;
 }
 
 html[dir='rtl'] .bubble-close {
   left: 6px;
   right: auto;
 }
 
 .bubble-close {
   background-image: -webkit-image-set(
-      url('../../../resources/default_100_percent/close_bar.png') 1x,
-      url('../../../resources/default_200_percent/close_bar.png') 2x);
+      url('../../../resources/default_100_percent/close_2.png') 1x,
+      url('../../../resources/default_200_percent/close_2.png') 2x);
 }
 
 .bubble-close:hover {
   background-image: -webkit-image-set(
-      url('../../../resources/default_100_percent/close_bar_hover.png') 1x,
-      url('../../../resources/default_200_percent/close_bar_hover.png') 2x);
+      url('../../../resources/default_100_percent/close_2_hover.png') 1x,
+      url('../../../resources/default_200_percent/close_2_hover.png') 2x);
 }
 
 .bubble-close:active {
   background-image: -webkit-image-set(
-    url('../../../resources/default_100_percent/close_bar_pressed.png') 1x,
-    url('../../../resources/default_200_percent/close_bar_pressed.png') 2x);
+      url('../../../resources/default_100_percent/close_2_pressed.png') 1x,
+      url('../../../resources/default_200_percent/close_2_pressed.png') 2x);
 }
 
 .bubble-shadow {
   bottom: 0;
   box-shadow: 0 2px 6px rgba(0, 0, 0, 0.15);
   left: 0;
   position: absolute;
   right: 0;
   top: 0;
   z-index: 1;
@@ skipping 20 matching lines @@
 
 .bubble-shadow,
 .bubble-content {
   border-radius: 6px;
   box-sizing: border-box;
 }
 
 .auto-close-bubble {
   position: fixed;
 }