AbstractWindowedCursor is not special.

Use the CrossProcessCursor interface in the way it was intended
without introducing special cases for AbstractWindowedCursor.
This is possible now that we do not distinguish between local-only
and remotable CursorWindows so we don't need to provide a window
to the AbstractWindowedCursor for it to fill; it can provide one
for itself if it wants one.

This logic makes it possible to create CrossProcessCursor
implementations that perform just as well as AbstractWindowedCursors.

Change-Id: I764b25ee6311d28c50d1930705346b265faec86a