Correct ChildAccountService child flag retrieval

Correct ChildAccountService child flag retrieval

This CL fixes two bugs in ChildAccountService's child flag retrieval:
* When flag fetching is disabled by command-line flag, causing all
  accounts to be marked as non-child, the flag status should be set
  to "known," not "unknown."
* When the flag is retrieved from the cloud, it should be stored
  before notifying callbacks waiting for the retrieval to finish.

This CL is a prerequisite for the test in crbug.com/477145.

BUG=477145
TEST=Tested as part of the new browser test in follow-up CL

Committed: https://crrev.com/fa8233aa24f47afdac436ad7340ef14a31263413
Cr-Commit-Position: refs/heads/master@{#326058}

[bartfab (slow), 2015-04-21 15:36:17]

bartfab@chromium.org changed reviewers:
+ merkulova@chromium.org

[bartfab (slow), 2015-04-21 15:36:18]

Hi Tatiana,

Please take a look.

[merkulova, 2015-04-21 15:38:34]

lgtm

[bartfab (slow), 2015-04-21 15:42:38]

bartfab@chromium.org changed reviewers:
+ treib@chromium.org

[bartfab (slow), 2015-04-21 15:42:38]

Hi Marc,

Please take a look.

[Marc Treib, 2015-04-21 15:59:02]

On 2015/04/21 15:42:38, bartfab wrote:
> Hi Marc,
> 
> Please take a look.

LGTM, and thanks for fixing our bugs!

[bartfab (slow), 2015-04-21 16:15:47]

The CQ bit was checked by bartfab@chromium.org

[bartfab (slow), 2015-04-21 16:15:47]

The patchset sent to the CQ was uploaded after l-g-t-m from
merkulova@chromium.org
Link to the patchset: https://codereview.chromium.org/1051273009/#ps20001
(title: "Add const.")

[commit-bot: I haz the power, 2015-04-21 16:16:09]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1051273009/20001

[bartfab (slow), 2015-04-21 16:18:46]

On 2015/04/21 15:59:02, Marc Treib wrote:
> On 2015/04/21 15:42:38, bartfab wrote:
> > Hi Marc,
> > 
> > Please take a look.
> 
> LGTM, and thanks for fixing our bugs!

Well, this is part of the fix for an M43 regression... :(

[commit-bot: I haz the power, 2015-04-21 17:11:49]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-04-21 17:12:55]

Patchset 2 (id:??) landed as
https://crrev.com/fa8233aa24f47afdac436ad7340ef14a31263413
Cr-Commit-Position: refs/heads/master@{#326058}