[MD] Change appearance of incognito NTP to MD spec.

chrome/browser/resources/ntp4/new_tab.js

Index: chrome/browser/resources/ntp4/new_tab.js
diff --git a/chrome/browser/resources/ntp4/new_tab.js b/chrome/browser/resources/ntp4/new_tab.js
index cb0c42dc9d0fcaf35773a4ffb6c77324a222436e..bce5b23db2511b6b711c04973177cbe6ac037597 100644
--- a/chrome/browser/resources/ntp4/new_tab.js
+++ b/chrome/browser/resources/ntp4/new_tab.js
@@ -333,8 +333,10 @@ cr.define('ntp', function() {
 
   /**
    * Called when the theme has changed.
+   * @param {Object} opt_themeData Not used; only exists to match equivalent
+   *     function in incognito NTP.
    */
-  function themeChanged() {
+  function themeChanged(opt_themeData) {
     $('themecss').href = 'chrome://theme/css/new_tab_theme.css?' + Date.now();
   }