[Sync] Make DirectoryBackingStore's db_ private.

[Sync] Make DirectoryBackingStore's db_ private.

This is a minor refactoring change.  See linked bug for related work.

In order to make db_ private we needed to:
  - Add accessors for common operations (IsOpen, etc.)
  - Make TestDirectoryBackingStore a friend so it can db_.release().

BUG=475557
Committed: https://crrev.com/dd12e9d5be29e54c54d382844d51874bd47ee22a
Cr-Commit-Position: refs/heads/master@{#325470}

[maniscalco, 2015-04-15 18:10:42]

maniscalco@chromium.org changed reviewers:
+ zea@chromium.org

[maniscalco, 2015-04-15 18:10:43]

Nicolas, would you please review this change?  It's the latest in a series of
Directory related cleanup patches.

https://codereview.chromium.org/1082423002/diff/1/sync/syncable/directory_bac...
File sync/syncable/directory_backing_store.h (right):

https://codereview.chromium.org/1082423002/diff/1/sync/syncable/directory_bac...
sync/syncable/directory_backing_store.h:47: friend class
TestDirectoryBackingStore;
TestDirectoryBackingStore is friend so it can .release() db_.  It may be
possible to change the way TDBS is use in tests to eliminate this friend, but I
think that's beyond the scope of this patch.

[Nicolas Zea, 2015-04-16 15:56:33]

lgtm

https://codereview.chromium.org/1082423002/diff/1/sync/syncable/directory_bac...
File sync/syncable/directory_backing_store.h (right):

https://codereview.chromium.org/1082423002/diff/1/sync/syncable/directory_bac...
sync/syncable/directory_backing_store.h:47: friend class
TestDirectoryBackingStore;
On 2015/04/15 18:10:43, maniscalco wrote:
> TestDirectoryBackingStore is friend so it can .release() db_.  It may be
> possible to change the way TDBS is use in tests to eliminate this friend, but
I
> think that's beyond the scope of this patch.

nit: these should all be within the private: section below

[maniscalco, 2015-04-16 16:03:46]

Thanks for the speedy review!

https://codereview.chromium.org/1082423002/diff/1/sync/syncable/directory_bac...
File sync/syncable/directory_backing_store.h (right):

https://codereview.chromium.org/1082423002/diff/1/sync/syncable/directory_bac...
sync/syncable/directory_backing_store.h:47: friend class
TestDirectoryBackingStore;
On 2015/04/16 15:56:33, Nicolas Zea wrote:
> On 2015/04/15 18:10:43, maniscalco wrote:
> > TestDirectoryBackingStore is friend so it can .release() db_.  It may be
> > possible to change the way TDBS is use in tests to eliminate this friend,
but
> I
> > think that's beyond the scope of this patch.
> 
> nit: these should all be within the private: section below

Done.

[maniscalco, 2015-04-16 16:03:52]

The CQ bit was checked by maniscalco@chromium.org

[maniscalco, 2015-04-16 16:03:52]

The patchset sent to the CQ was uploaded after l-g-t-m from zea@chromium.org
Link to the patchset: https://codereview.chromium.org/1082423002/#ps20001
(title: "Move friend declarations to private section.")

[commit-bot: I haz the power, 2015-04-16 16:04:55]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1082423002/20001

[commit-bot: I haz the power, 2015-04-16 17:39:00]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-04-16 17:39:51]

Patchset 2 (id:??) landed as
https://crrev.com/dd12e9d5be29e54c54d382844d51874bd47ee22a
Cr-Commit-Position: refs/heads/master@{#325470}