The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/1118ffeaa9335b10faf86e3ee4bfb83a3d34ce86

commit 1118ffeaa9335b10faf86e3ee4bfb83a3d34ce86
Author: Tim Sergeant <tsergeant@chromium.org>
Date: Fri Jul 28 06:20:51 2017

MD Bookmarks: Open bookmark items on middle click.

This allows bookmarks to be opened in a new background tab on
middle-click, or in a new foreground tab on shift middle-click,
mimicking the behavior of a native link.

Bug:  729856 
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: I85c81d3a8fb412bccf2fe28874a8e41325c3551c
Reviewed-on: https://chromium-review.googlesource.com/590393
Reviewed-by: calamity <calamity@chromium.org>
Commit-Queue: Tim Sergeant <tsergeant@chromium.org>
Cr-Commit-Position: refs/heads/master@{#490298}
[modify] https://crrev.com/1118ffeaa9335b10faf86e3ee4bfb83a3d34ce86/chrome/browser/resources/md_bookmarks/item.html
[modify] https://crrev.com/1118ffeaa9335b10faf86e3ee4bfb83a3d34ce86/chrome/browser/resources/md_bookmarks/item.js
[modify] https://crrev.com/1118ffeaa9335b10faf86e3ee4bfb83a3d34ce86/chrome/test/data/webui/md_bookmarks/command_manager_test.js
[modify] https://crrev.com/1118ffeaa9335b10faf86e3ee4bfb83a3d34ce86/chrome/test/data/webui/md_bookmarks/test_util.js