Refresh the Incognito NTP layout on default font size change

chrome/browser/ui/webui/ntp/new_tab_ui.h

 // 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.
 
 #ifndef CHROME_BROWSER_UI_WEBUI_NTP_NEW_TAB_UI_H_
 #define CHROME_BROWSER_UI_WEBUI_NTP_NEW_TAB_UI_H_
 
 #include "base/macros.h"
 #include "base/strings/string16.h"
 #include "components/prefs/pref_change_registrar.h"
@@ skipping 56 matching lines @@
     std::string GetContentSecurityPolicyChildSrc() const override;
 
    private:
     // Pointer back to the original profile.
     Profile* profile_;
 
     DISALLOW_COPY_AND_ASSIGN(NewTabHTMLSource);
   };
 
   void OnShowBookmarkBarChanged();
+  void OnDefaultFontSizeChanged();
 
   Profile* GetProfile() const;
 
   PrefChangeRegistrar pref_change_registrar_;
 
   DISALLOW_COPY_AND_ASSIGN(NewTabUI);
 };
 
 #endif  // CHROME_BROWSER_UI_WEBUI_NTP_NEW_TAB_UI_H_