Implement EXTRA_HAS_MORE and EXTRA_REQUEST_MORE contract with
document providers. Providers can include EXTRA_HAS_MORE when
additional data is available with additional cost, such as a network
request.
Listen to content changes based on returned cursor instead of
original Uri. Include a test backend to exercise. UX still under
development.
Bug: 10350207
Change-Id: Iaa8954df55a1a1c0aa96eb8a4fd288e12c2fbb01
b448660a22