The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/c4f9f1387f4253aa2afcc70b5d3d79eba441aff8

commit c4f9f1387f4253aa2afcc70b5d3d79eba441aff8
Author: dpapad <dpapad@chromium.org>
Date: Mon Oct 30 20:40:17 2017

MD Extensions: Remove usage of paper-item.

This eliminates usage of the deprecated paper-item, and also reduces the
size of the optimized HTML file by 2kb (236->234).

Bug:  778877 
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: I688b1ed7eb603ee6fa81e17a6956dce869519704
Reviewed-on: https://chromium-review.googlesource.com/742322
Commit-Queue: Demetrios Papadopoulos <dpapad@chromium.org>
Reviewed-by: Dave Schuyler <dschuyler@chromium.org>
Cr-Commit-Position: refs/heads/master@{#512613}
[modify] https://crrev.com/c4f9f1387f4253aa2afcc70b5d3d79eba441aff8/chrome/browser/resources/md_extensions/sidebar.html
[modify] https://crrev.com/c4f9f1387f4253aa2afcc70b5d3d79eba441aff8/chrome/test/data/webui/extensions/extension_sidebar_test.js