Make PEM debugging section fixed width in the SSL interstitial

components/security_interstitials/core/browser/resources/interstitial_v2.js

 // 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.
 
 // This is the shared code for the new (Chrome 37) security interstitials. It is
 // used for both SSL interstitials and Safe Browsing interstitials.
 
 var expandedDetails = false;
 var keyPressState = 0;
 
@@ skipping 50 matching lines @@
     keyPressState = 0;
   }
 }
 
 /**
  * This appends a piece of debugging information to the end of the warning.
  * When complete, the caller must also make the debugging div
  * (error-debugging-info) visible.
  * @param {string} title  The name of this debugging field.
  * @param {string} value  The value of the debugging field.
+ * @param {string=} extraCssClass Additional CSS classes. Optional.

[lgarron, 2016/10/14 21:33:05]

Nit: I just noticed that this is an incorrect plural. Could you change to
"Additional CSS class" (unless you want to turn this parameter into a list)?

[meacer, 2016/10/14 21:44:37]

Changed the param to a boolean and renamed it.

  */
-function appendDebuggingField(title, value) {
+function appendDebuggingField(title, value, extraCssClass) {

[felt, 2016/10/14 21:32:33]

Do you plan to use this for other things in the future? If not, would it be
easier to read this in the future if it just directly said |fixedWidth| and had
a bool?

[meacer, 2016/10/14 21:44:37]

Not sure if we'll need new stuff, but to keep it simple let's make it
fixedWidth.

   // The values input here are not trusted. Never use innerHTML on these
   // values!
   var spanTitle = document.createElement('span');
   spanTitle.classList.add('debugging-title');
   spanTitle.innerText = title + ': ';
 
   var spanValue = document.createElement('span');
   spanValue.classList.add('debugging-value');
+  if (extraCssClass) {
+    spanValue.classList.add(extraCssClass);
+  }
   spanValue.innerText = value;
 
   var pElem = document.createElement('p');
   pElem.classList.add('debugging-content');
   pElem.appendChild(spanTitle);
   pElem.appendChild(spanValue);
   $('error-debugging-info').appendChild(pElem);
 }
 
 function toggleDebuggingInfo() {
@@ skipping 111 matching lines @@
     });
   }
 
   preventDefaultOnPoundLinkClicks();
   setupExtendedReportingCheckbox();
   setupSSLDebuggingInfo();
   document.addEventListener('keypress', handleKeypress);
 }
 
 document.addEventListener('DOMContentLoaded', setupEvents);