Fix 6360834 Select All is shown in place of Deselect all option

The CL changes the SelectionManager's toggle method so it changes itself to
inverse selection mode when all items are already selected, and onSelectionModeChange
will be triggered so the listener can update the selection menu (Select all/Deselect all)
and ActionBar.

Change-Id: I570a299cc8fd7d1d5acab948f9c6531a9adde486
b: 6360834