GitLab

The top level reading list folder is not editable/movable. The reading
list articles is editable since we need to support move and delete for
them.

Test is adjusted to ensure no overflow menu is shown for the
reading list folder.

Also this CL is needed for a following CL to adjust positioning logic.

Bug: 1139070
Change-Id: Ia09626c4568fe1e90612256da53176a90fc19c5c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2481959
Commit-Queue: Xing Liu <xingliu@chromium.org>
Reviewed-by: Theresa  <twellington@chromium.org>
Cr-Commit-Position: refs/heads/master@{#818530}