Merge cros: Fix unexpected cryptohome failure UI

Merge cros: Fix unexpected cryptohome failure UI

> TokenHandleFetcher::FillForNewUser should be called when there is no
> existing TokenHandle. Existing users should all go through the
> BackfillToken path. This would let the login screen code test against
> existing TokenHandle rather than racing with FillForNewUser code.
>
> BUG=596502
>
> Review URL: https://codereview.chromium.org/1824693002
>
> Cr-Commit-Position: refs/heads/master@{#382342}
> (cherry picked from commit 9231ba274a1c6525bf06cfc1a214fae2967663b7)

Committed: https://chromium.googlesource.com/chromium/src/+/43d3155e38ae1890b8776731c3fcffcb44ef46b6

[xiyuan, 2016-03-21 19:39:35]

Description was changed from

==========
Merge cros: Fix unexpected cryptohome failure UI

> TokenHandleFetcher::FillForNewUser should be called when there is no
> existing TokenHandle. Existing users should all go through the
> BackfillToken path. This would let the login screen code test against
> existing TokenHandle rather than racing with FillForNewUser code.
>
> BUG=596502
>
> Review URL: https://codereview.chromium.org/1824693002
>
> Cr-Commit-Position: refs/heads/master@{#382342}
> (cherry picked from commit 9231ba274a1c6525bf06cfc1a214fae2967663b7)
==========

to

==========
Merge cros: Fix unexpected cryptohome failure UI

> TokenHandleFetcher::FillForNewUser should be called when there is no
> existing TokenHandle. Existing users should all go through the
> BackfillToken path. This would let the login screen code test against
> existing TokenHandle rather than racing with FillForNewUser code.
>
> BUG=596502
>
> Review URL: https://codereview.chromium.org/1824693002
>
> Cr-Commit-Position: refs/heads/master@{#382342}
> (cherry picked from commit 9231ba274a1c6525bf06cfc1a214fae2967663b7)

Committed:
https://chromium.googlesource.com/chromium/src/+/43d3155e38ae1890b8776731c3fc...
==========

[xiyuan, 2016-03-21 19:39:37]

Committed patchset #1 (id:1) manually as
43d3155e38ae1890b8776731c3fcffcb44ef46b6.