Making the clipboard work across users.

Making the clipboard work across users.

When copying from the parent: the ClipData can be pasted in the managed profile.
When copying from a managed profile: it can be pasted in the parent,
unless the policies says it's disabled. In which case, the clipboard of the parent becomes empty.
Supporting content uris.

BUG: 15186236

Change-Id: I522564a7c07ff21df137adcda980bb52e5739964