Resubmit: Add a Restore() method to ValueStore and make StorageAPI use it

Resubmit: Add a Restore() method to ValueStore and make StorageAPI use it

Resubmit of: https://codereview.chromium.org/165223003/

TBR=mpcomplete@chromium.org
TBR=joaodasilva@chromium.org

---------------------------------
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=253353

[Devlin, 2014-02-25 19:39:36]

Ben, please review the fix.  I'll send it through the trybots a few more times
to make sure, but it looks like this was it.

https://codereview.chromium.org/176963006/diff/1/chrome/browser/extensions/ap...
File chrome/browser/extensions/api/storage/storage_api.cc (right):

https://codereview.chromium.org/176963006/diff/1/chrome/browser/extensions/ap...
chrome/browser/extensions/api/storage/storage_api.cc:28:
tried_restoring_storage_(false) {}
So, after more debugging than I'd like to admit, I realized I forgot to set this
variable.  Which somehow, was always kind enough to be "false" on Linux, but on
windows, sometimes went to "true", making us skip the restoration step.  Gah.

[not at google - send to devlin, 2014-02-25 20:39:19]

lgtm

https://codereview.chromium.org/176963006/diff/1/chrome/browser/extensions/ap...
File chrome/browser/extensions/api/storage/storage_api.cc (right):

https://codereview.chromium.org/176963006/diff/1/chrome/browser/extensions/ap...
chrome/browser/extensions/api/storage/storage_api.cc:28:
tried_restoring_storage_(false) {}
On 2014/02/25 19:39:36, D Cronin wrote:
> So, after more debugging than I'd like to admit, I realized I forgot to set
this
> variable.  Which somehow, was always kind enough to be "false" on Linux, but
on
> windows, sometimes went to "true", making us skip the restoration step.  Gah.

Heh been there :)

[Devlin, 2014-02-25 22:03:47]

The CQ bit was checked by rdevlin.cronin@chromium.org

[commit-bot: I haz the power, 2014-02-25 22:32:24]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/rdevlin.cronin@chromium.org/176963006/1

[commit-bot: I haz the power, 2014-02-25 23:42:27]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/rdevlin.cronin@chromium.org/176963006/1

[commit-bot: I haz the power, 2014-02-26 04:58:06]

Change committed as 253353