GitLab

OBB backup/ restore is no longer handled within the target app
process.  This is done to avoid having to require that OBB-using
apps have full read/write permission for external storage.

The new OBB backup service is a new component running in the
same app as the already-existing shared storage backup agent.
The backup infrastructure delegates backup/restore of apps'
OBB contents to this component (because the system process
may not itself read/write external storage).

From the command line, OBB backup is enabled by using new
-obb / -noobb flags with adb backup.  The default is noobb.

Finally, a couple of nit fixes:

- buffer-size mismatch between the writer and reader of chunked
  file data has been corrected; now the reading side won't be
  issuing an extra pipe read per chunk.

- bu now explicitly closes the transport socket fd after
  adopting it. This was benign but triggered a logged
  warning about leaked fds.

(Cherrypicked)

Change-Id: I471f6348abcccb7bf1e1710b7beda9f23de53e14