Rotate the interstitial bypass keyword

The security interstitial bypass keyword hasn't changed in two years and
awareness of the bypass has been increased in blogs and social media.
Rotate the keyword to help prevent misuse.

Bug: 797344
Change-Id: I76213b05cc0fe8f23882123d0aeef668652dd89d
Reviewed-on: https://chromium-review.googlesource.com/860418
Reviewed-by: Adrienne Porter Felt <felt@chromium.org>
Commit-Queue: Eric Lawrence <elawrence@chromium.org>
Cr-Commit-Position: refs/heads/master@{#528371}
diff --git a/components/security_interstitials/core/browser/resources/interstitial_large.js b/components/security_interstitials/core/browser/resources/interstitial_large.js
index 066e8b6..0fa7dbf 100644
--- a/components/security_interstitials/core/browser/resources/interstitial_large.js
+++ b/components/security_interstitials/core/browser/resources/interstitial_large.js
@@ -13,7 +13,10 @@
  * @param {string} e The key that was just pressed.
  */
 function handleKeypress(e) {
-  var BYPASS_SEQUENCE = 'thisisnotsafe';
+  // HTTPS errors are serious and should not be ignored. For testing purposes,
+  // other approaches are both safer and have fewer side-effects.
+  // See https://goo.gl/ZcZixP for more details.
+  var BYPASS_SEQUENCE = window.atob('dGhpc2lzdW5zYWZl');
   if (BYPASS_SEQUENCE.charCodeAt(keyPressState) == e.keyCode) {
     keyPressState++;
     if (keyPressState == BYPASS_SEQUENCE.length) {