Request more documents when EXTRA_HAS_MORE.

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
7 files changed
tree: 566abf34fc0eb5ade1aa6fdf1c55646f4a9787f7
  1. res/
  2. src/
  3. Android.mk
  4. AndroidManifest.xml