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

Review URL: https://codereview.chromium.org/175853002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@252652 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 252652