The operations of the remote renderer have to be performed in order, open, render some pages, close. One of the tasks was executed on the wrong executor resuling in a race and an occassional bad state. Also fixed a NPE if the preview list is flinged and then the user presses back. bug:17537922 Change-Id: I5048078ba2b875a2a8335f3a4324afaa34d014a2