Add message and image to NTP to promote extensions and bookmark sync....

chrome/browser/resources/new_tab_theme.css

 html {
   background-image: url(chrome://theme/theme_ntp_background?$1);
   background-color: $2; /* COLOR_NTP_BACKGROUND */
   background-position: $3;
   background-repeat: $5;
   overflow: hidden;
 }
 
 html[bookmarkbarattached='true'] {
   background-position: $4;
@@ skipping 83 matching lines @@
   color: $9; /* COLOR_NTP_LINK */
 }
 
 :link,
 :visited,
 .link,
 .list > .thumbnail-container {
   color: $$6; /* COLOR_NTP_LINK_UNDERLINE */
 }
 
-#themes-promo {
+#promo-line {
+  display: $$9;
+}
+
+#bottom-right-promo {
   display: $$8;
-}
+}