Make sure snap_page combined iframe serialized dom

telemetry/third_party/snap-it/popup.js

 document.addEventListener('DOMContentLoaded', function() {
   if (document.getElementById('button')) {
     document.getElementById('button').addEventListener('click', click);
   }
 });
 
 function click() {
   var messages = []
   var results;
   chrome.runtime.onMessage.addListener(function(message, sender, sendResponse) {
@@ skipping 15 matching lines @@
 
   var a = document.getElementById('button');
   a.className = 'serialize';
   a.innerHTML = 'Serializing...';
   a.removeEventListener('click', click);
 }
 
 /**
  * Takes all the responses from the injected content scripts and creates the
  * HTML file for download.
- * 
+ *
  * @param {Array<Object>} messages The response from all of the injected content
  *     scripts.
  */
 function completeProcess(messages) {
   var html = outputHTMLString(messages);
   var file = new Blob([html], {type: 'text/html'});
   var url = URL.createObjectURL(file);
 
   var a = document.getElementById('button');
   a.className = 'download';
   a.innerHTML = 'Download';
   a.href = url;
   a.download = "snap-it.html";
 }
 
 /**
  * Converts the responses from the injected content scripts into a string
  * representing the HTML.
- * 
+ *
  * @param {Array<Object>} messages The response from all of the injected content
  *     scripts.
  * @return {string} The resulting HTML.
  */
 function outputHTMLString(messages) {
   var rootIndex = 0;
   for (var i = 1; i < messages.length; i++) {
     rootIndex = messages[i].frameIndex === '0' ? i : rootIndex;
   }
   fillRemainingHolesAndMinimizeStyles(messages, rootIndex);
@@ skipping 29 matching lines @@
  *
  * @param {Object} message The message Object whose style attributes should be
  *     minimized.
  */
 function minimizeStyles(message) {
   var nestingDepth = message.frameIndex.split('.').length - 1;
   var iframe = document.createElement('iframe');
   document.body.appendChild(iframe);
   iframe.setAttribute(
       'style',
-      `height: ${message.windowHeight}px;` + 
+      `height: ${message.windowHeight}px;` +
       `width: ${message.windowWidth}px;`);
 
   var html = message.html.join('');
   html = unescapeHTML(html, nestingDepth);
   iframe.contentDocument.documentElement.innerHTML = html;
   var doc = iframe.contentDocument;
 
   // Remove entry in |message.html| where extra style element was specified.
   message.html[message.pseudoElementTestingStyleIndex] = '';
   var finalPseudoElements = [];
@@ skipping 205 matching lines @@
   }
   return html;
 }
 
 /**
  * Calculate the correct encoding of a quotation mark that should be used given
  * the nesting depth of the window in the frame tree.
  *
  * @param {number} depth The nesting depth of the appropriate window in the
  *     frame tree.
- * @return {string} The correctly escaped string. 
+ * @return {string} The correctly escaped string.
  */
 function escapedQuote(depth) {
   if (depth == 0) {
     return '"';
   } else {
     var arr = 'amp;'.repeat(depth-1);
     return '&' + arr + 'quot;';
   }
 }