Reworking MessageListFragment.

- Now MessageListFragment uses loaders to load data.

- Now that we use Loader's auto-requery with throttling,
  removed the throttling timer from MessagesAdapter.

- Simplified footer mode.  (now only "no footer" or "load more")

- Removed saving/restoring list state code.
  These method don't really look like working, or at least
  not always working.  Now that UI's lifecycle is changing,
  we'd better redo it from scratch.

- Removed MessageListUnitTests.
  It only has tests for onSaveInstanceState/restore of the fragment,
  which I virtually disabled.

And minor clean-ups
- Moved the code to save/restore selected state from the fragment
  to Adapter.

Bug 2911766
Bug 2897500

Change-Id: I16c7aefecc5409c57fc5fc8c59b5c80d9b7fc164
1 file changed