Hide the default checkbox on Safe Browsing interstitials

chrome/browser/resources/ssl/interstitial_v2.css

 /* Copyright 2014 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. */
 
 a {
   color: #585858;
 }
 
 body {
   background-color: #f7f7f7;
@@ skipping 72 matching lines @@
 }
 
 .icon {
   background-repeat: no-repeat;
   background-size: 100%;
   height: 72px;
   margin: 0 0 40px;
   width: 72px;
 }
 
+input[type=checkbox] {
+  visibility: hidden;
+}
+
 .interstitial-wrapper {
   box-sizing: border-box;
   font-size: 1em;
   line-height: 1.6em;
   margin: 100px auto 0;
   max-width: 600px;
   width: 100%;
 }
 
 #malware-opt-in {
@@ skipping 157 matching lines @@
   }
 
   .nav-wrapper {
     margin-top: 30px;
   }
 
   .small-link {
     font-size: 1em;
   }
 }