chrome/browser/resources/sync_internals/data.html

<p><strong>Some personal info may be in the data dump.  An option to
redact sensitive info will be added in the future, but until then, be
careful about posting data dumps on bug reports.</strong></p>

<!-- TODO(akalin): Add option to redact sensitive info. -->

<button id="dump-to-text">Dump to text</button>

<pre id="data-dump"></pre>

<script>
(function() {
var dumpToTextButton = document.getElementById('dump-to-text');
var dataDump = document.getElementById('data-dump');
dumpToTextButton.addEventListener('click', function(event) {
  // TODO(akalin): Add info like Chrome version, OS, date dumped, etc.

  var data = '';
  data += '======\n';
  data += 'Status\n';
  data += '======\n';
  data += JSON.stringify(chrome.sync.aboutInfo, null, 2);
  data += '\n';
  data += '\n';

  data += '=============\n';
  data += 'Notifications\n';
  data += '=============\n';
  data += JSON.stringify(chrome.sync.notifications, null, 2);
  data += '\n';
  data += '\n';

  data += '===\n';
  data += 'Log\n';
  data += '===\n';
  data += JSON.stringify(chrome.sync.log.entries, null, 2);
  data += '\n';

  dataDump.textContent = data;
});
})();
</script>