Revert of Sync: Refactoring of DEVICE_INFO syncable type - Part 1

Revert of Sync: Refactoring of DEVICE_INFO syncable type - Part 1 (https://codereview.chromium.org/367153005/)

Reason for revert:
this broke unit_tests" on "Linux ASan LSan Tests (2):
http://build.chromium.org/p/chromium.memory/builders/Linux%20ASan%20LSan%20Tests%20%282%29/builds/4967.

Original issue's description:
> Sync: Refactoring of DEVICE_INFO syncable type - Part 1
> 
> This change introduces a new class LocalDeviceInfoProvider that is responsible
> for providing the local device specific DeviceInfo/cache_guid. It initializes
> the data asynchronously and allows consumers to get notified when the data 
> becomes available. 
> 
> LocalDeviceInfoProvider will allow to remove these responsibilities from 
> SyncedDeviceTracker / ProfileSyncService and loose coupling between
> ProfileSyncService and a number of SyncableService and DataTypeController 
> derived classes.
> 
> LocalDeviceInfoProvider is hosted on the frontend thread. Since it needs
> cache_guid to initialize DeviceInfo, which is currently available only on the
> backend, I updated SyncBackendHostCore and SyncBackendHostImpl to pass
> cache_guid to the frontend via OnBackendInitialized.
> 
> For the time being SyncedDeviceTracker remains unchanged
> and continues to initialize the local device info too. The entire class will be
> removed in the Part 2 of the change which will move SyncedDeviceTracker
> functionality to a new SyncableService.
> 
> LocalDeviceInfoProvider also replaces SessionsSyncManager::SyncInternalApiDelegate
> which was previously used to decouple SessionsSyncManager from the specifics of
> of the local device info implementation. 
> SessionsSyncManager is changed to consume LocalDeviceInfoProvider instead of 
> SessionsSyncManager::SyncInternalApiDelegate.
> SessionDataTypeController now also consumes LocalDeviceInfoProvider to make sure
> that SESSIONS type model doesn't start before local device info becomes available.
> A very similar approach will be used in the upcoming second part of the change
> for DEVICE_INFO DataTypeController and SyncableType.
> 
> The change includes new unit tests for LocalDeviceInfoProvider and
> SessionDataTypeController.
> 
> Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=283461

TBR=zea@chromium.org,rlarocque@chromium.org,sky@chromium.org,maniscalco@chromium.org,stanisc@chromium.org
NOTREECHECKS=true
NOTRY=true

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=283475

[kuan, 2014-07-16 19:57:50]

Created Revert of Sync: Refactoring of DEVICE_INFO syncable type - Part 1

[commit-bot: I haz the power, 2014-07-16 20:00:59]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/kuan@chromium.org/401433003/1

[commit-bot: I haz the power, 2014-07-16 20:04:13]

Change committed as 283475