views: use open folder icon for open treeview folders

Bug: 610428
Change-Id: I91726bc0f69193914e373f34618436f3d175fac0
Reviewed-on: https://chromium-review.googlesource.com/757074
Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Elly Fong-Jones <ellyjones@chromium.org>
Cr-Commit-Position: refs/heads/master@{#514630}
1 file changed