ntp: remove default thumbnail for most visited (broken camera)

chrome/browser/resources/ntp4/new_tab_theme.css

 /* Copyright (c) 2011 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.
  */
 
 html,
 #most-visited-settings {
   background-attachment: fixed;
   background-color: $2;  /* COLOR_NTP_BACKGROUND */
   background-image: url(chrome://theme/IDR_THEME_NTP_BACKGROUND?$1);
@@ skipping 72 matching lines @@
 .most-visited,
 .most-visited > .title {
   color: $8;  /* COLOR_NTP_TEXT */
 }
 
 .most-visited:focus:not(.filler) .thumbnail-wrapper,
 .most-visited:hover:not(.filler) .thumbnail-wrapper {
   background-color: $6;  /* COLOR_NTP_HEADER */
 }
 
-.edit-bar {
-  background-image: -webkit-linear-gradient(
-                        $7,  /* COLOR_HEADER_GRADIENT_LIGHT */
-                        $6);  /* COLOR_NTP_HEADER */
-}
-
 .thumbnail-wrapper {
   /* This shows through at the (rounded) thumbnail's corners. */
   background-color: $11;  /* COLOR_NTP_SECTION_BORDER */
 }
 
 .filler .thumbnail {
   border-color: $2;  /* COLOR_NTP_BACKGROUND */
 }