Allows applications to propagate multiple URI grants through an
Intent.
Later on, we should probably redefine the share actions to be
based on this ClipData with the old extras-based approach only
there for compatibility. Even if we don't do that, though, this
allows you to do a multi-select share that grants multiple URI
permissions by stuffing the URIs in a ClipData.
Also add some documentation in various places telling people how
they can grant URI permissions.
Change-Id: Id4ba8e72c11caf7e1f1f438cb7af058d1586a37c
21c241e061