GitLab

This change makes the Managed Bookmarks folder visible in the bookmarks
bar if it contains at least one bookmark:

- this folder is always shown floating to the left, next to the Apps button;
- this folder also appears in the bookmarks menu from the hotdog menu, as if
  it were part of the bookmarks bar;
- bookmarks can't be dragged into this folder or any of its subfolders;
- dragging bookmarks out of this folder always creates a new copy and never
  moves (the mouse cursor is decorated with the + "copy" indicator);
- the bookmark editor can't select managed folders for new bookmarks;
- bookmarks a page that already has a managed bookmarks creates a new
  bookmark instead.

BUG=49598
R=sky@chromium.org

Review URL: https://codereview.chromium.org/302313005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@275676 0039d316-1c4b-4281-b951-d872f2087c98