The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/19c32887d6bb6f7a93a89e76f1944c6a18afcc91

commit 19c32887d6bb6f7a93a89e76f1944c6a18afcc91
Author: Christopher Lam <calamity@chromium.org>
Date: Thu Sep 07 06:37:15 2017

[MD Bookmarks] Scroll bookmark list and sidebar on drag hover.

This CL makes internal drags in the bookmark manager scroll the sidebar
and bookmark list when the drag is hovered over the bottom or top of the
scrollable sections.

Bug:  748944 
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: I699b0dff3f410ae9fc856e0bc476f08837854d60
Reviewed-on: https://chromium-review.googlesource.com/647393
Reviewed-by: Tim Sergeant <tsergeant@chromium.org>
Commit-Queue: calamity <calamity@chromium.org>
Cr-Commit-Position: refs/heads/master@{#500236}
[modify] https://crrev.com/19c32887d6bb6f7a93a89e76f1944c6a18afcc91/chrome/browser/resources/md_bookmarks/dnd_manager.js