code: 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";
  }
docs: 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.