NTP update for ChromeOS.

chrome/browser/resources/new_tab_theme.css

 html,
 .section > h2 span,
 #most-visited-settings {
   background-attachment: fixed;
   background-color: $2; /* COLOR_NTP_BACKGROUND */
   background-image: url(chrome://theme/IDR_THEME_NTP_BACKGROUND?$1);
   background-position: $3;
   background-repeat: $5;
 }
 
@@ skipping 98 matching lines @@
 
 .section:not(.hidden) > h2 {
   color: $$8; /* COLOR_NTP_SECTION_HEADER_TEXT_HOVER */
 }
 
 .section.hidden:not([noexpand]) > h2:hover,
 #closed-sections-bar > button:hover {
   color: $$8; /* COLOR_NTP_SECTION_HEADER_TEXT_HOVER */
 }
 
-.section > h2 .back {
+.section > h2 .back,
+#closed-sections-bar[chromeos] {
   border-top: 1px solid $$1; /* COLOR_NTP_SECTION  */
 }
 
 .section.hidden > h2 .back {
   background: none;
   border-color-top: $$$1; /* COLOR_NTP_SECTION_HEADER_RULE_LIGHT */
 }
 
 .section.hidden:hover > h2 .back {
   border-color-top: $$9; /* COLOR_NTP_SECTION_HEADER_RULE */
 }
 
 .app a {
   color: $8; /* COLOR_NTP_TEXT */
 }
 
 .app:hover > a {
   color: $$3; /* COLOR_NTP_SECTION_TEXT */
   background-color: $$1; /* COLOR_NTP_SECTION */;
 }
 
 #apps-promo-hide {
   color: $9; /* COLOR_NTP_LINK */
 }
 
 #apps-promo-text2 {
   color: $$$3; /* COLOR_NTP_TEXT_LIGHT */
 }