Revert of Add a Restore() method to ValueStore and make StorageAPI use it

Revert of Add a Restore() method to ValueStore and make StorageAPI use it (https://codereview.chromium.org/165223003/)

Reason for revert:
Broke win unit_tests with StorageApiUnittest.RestoreStorage

Original issue's description:
> Add a Restore() method to ValueStore and make StorageAPI use it
> Take the first steps in preventing the Storage from getting and staying
> corrupted. This lets us Restore() a ValueStore when it's corrputed, and tries to
> do so in the StorageAPI calls.
> This also refactors so that there's a Local and Sync SettingsBackend - this has
> the added advantage of meaning we don't decorate the Local stores with Sync
> behavior.
> BUG=261623
> 
> Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=252617

TBR=mpcomplete@chromium.org,kalman@chromium.org,joaodasilva@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=261623
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=252652

[Devlin, 2014-02-21 21:38:50]

Created Revert of Add a Restore() method to ValueStore and make StorageAPI use
it

[commit-bot: I haz the power, 2014-02-21 21:41:21]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/rdevlin.cronin@chromium.org/175853002/1

[commit-bot: I haz the power, 2014-02-21 21:44:49]

Change committed as 252652