Revert of Reimplement AccountManagerHelper singleton instance creation

Revert of Reimplement AccountManagerHelper singleton instance creation (patchset #4 id:180001 of https://codereview.chromium.org/2747293005/ )

Reason for revert:
Caused multiple bot failures, see crbug.com/710901.

Original issue's description:
> Reimplement AccountManagerHelper singleton instance creation
> 
> Current implementation of AccountManagerHelper can instantiate wrong delegate
> type if get() is called in too early. This CL fixes it. AtomicReference is used
> to avoid relying on external synchronization, because get() can be called
> from different threads. This CL also adds
> AccountManagerHelper.resetAccountManagerHelperForTests method that makes sure
> there's no interference between tests.
> 
> BUG=698258
> 
> Review-Url: https://codereview.chromium.org/2747293005
> Cr-Commit-Position: refs/heads/master@{#463963}
> Committed: https://chromium.googlesource.com/chromium/src/+/1305003fecaca059c4e3a5678eb48f0a00a46317

TBR=rogerta@chromium.org,nyquist@chromium.org,bsazonov@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=698258
Review-Url: https://codereview.chromium.org/2817723002
Cr-Commit-Position: refs/heads/master@{#464058}
Committed: https://chromium.googlesource.com/chromium/src/+/d02c080f54d8aca7e1827374177c17f4ad68a593

[Donn Denman, 2017-04-12 16:39:07]

The CQ bit was checked by donnd@chromium.org

[Donn Denman, 2017-04-12 16:39:08]

Created Revert of Reimplement AccountManagerHelper singleton instance creation

[commit-bot: I haz the power, 2017-04-12 16:39:49]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[nyquist, 2017-04-12 16:58:30]

lgtm

[commit-bot: I haz the power, 2017-04-12 17:04:44]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1492015147938470, "parent_rev":
"e9c64a91ffa876438944769b5921d171b5390cc8", "commit_rev":
"d02c080f54d8aca7e1827374177c17f4ad68a593"}

[commit-bot: I haz the power, 2017-04-12 17:05:36]

Description was changed from

==========
Revert of Reimplement AccountManagerHelper singleton instance creation (patchset
#4 id:180001 of https://codereview.chromium.org/2747293005/ )

Reason for revert:
Caused multiple bot failures, see crbug.com/710901.

Original issue's description:
> Reimplement AccountManagerHelper singleton instance creation
> 
> Current implementation of AccountManagerHelper can instantiate wrong delegate
> type if get() is called in too early. This CL fixes it. AtomicReference is
used
> to avoid relying on external synchronization, because get() can be called
> from different threads. This CL also adds
> AccountManagerHelper.resetAccountManagerHelperForTests method that makes sure
> there's no interference between tests.
> 
> BUG=698258
> 
> Review-Url: https://codereview.chromium.org/2747293005
> Cr-Commit-Position: refs/heads/master@{#463963}
> Committed:
https://chromium.googlesource.com/chromium/src/+/1305003fecaca059c4e3a5678eb4...

TBR=rogerta@chromium.org,nyquist@chromium.org,bsazonov@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=698258
==========

to

==========
Revert of Reimplement AccountManagerHelper singleton instance creation (patchset
#4 id:180001 of https://codereview.chromium.org/2747293005/ )

Reason for revert:
Caused multiple bot failures, see crbug.com/710901.

Original issue's description:
> Reimplement AccountManagerHelper singleton instance creation
> 
> Current implementation of AccountManagerHelper can instantiate wrong delegate
> type if get() is called in too early. This CL fixes it. AtomicReference is
used
> to avoid relying on external synchronization, because get() can be called
> from different threads. This CL also adds
> AccountManagerHelper.resetAccountManagerHelperForTests method that makes sure
> there's no interference between tests.
> 
> BUG=698258
> 
> Review-Url: https://codereview.chromium.org/2747293005
> Cr-Commit-Position: refs/heads/master@{#463963}
> Committed:
https://chromium.googlesource.com/chromium/src/+/1305003fecaca059c4e3a5678eb4...

TBR=rogerta@chromium.org,nyquist@chromium.org,bsazonov@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=698258

Review-Url: https://codereview.chromium.org/2817723002
Cr-Commit-Position: refs/heads/master@{#464058}
Committed:
https://chromium.googlesource.com/chromium/src/+/d02c080f54d8aca7e1827374177c...
==========

[commit-bot: I haz the power, 2017-04-12 17:05:37]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/d02c080f54d8aca7e1827374177c...