linux_aura: Make panels sticky to all workspaces.

This was the behavior in the GTK port. Replicating it in the views based
linux_aura.

BUG=339399

Review URL: https://codereview.chromium.org/171563006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@252227 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 252227