Enforcing that only uri grants work across users (not permissions).
Fixing a security hole where malicious Apps could access a uri if they had uri grants to the same uri on another user.
Enforcing that userIds in uris, if they exist, are the one of the ContentProvider.
BUG: 16779492
Change-Id: Iaa5264bd6c3aa0e15be3a4a64f9dc88238e0cb2e