Revert of ChildAccountService[Java] delegates everything to native side.

Revert of ChildAccountService[Java] delegates everything to native side. (patchset #2 id:20001 of https://codereview.chromium.org/1341423005/ )

Reason for revert:
This patch breaks git on case-insensitive filesystems.

Original issue's description:
> ChildAccountService[Java] delegates everything to native side.
> 
> Most of the child account detection/enforcement logic has been divided amongst
> the ChildAccountInfoFetcher and ForcedSigninProcessor.
> 
> ForcedSigninProcessor will make sure that child accounts are detected and
> are signed in.
> ChildAccountInfoFetcher only activates on signin and informs the
> native ChildAccountService about the child account and takes responsiblity for
> any further updates (graduation) or account changes.
> 
> Depends on http://crrev.com/1357643002
> Dependent patchset http://crrev.com/1353393002
> 
> BUG=518830
> 
> Committed: https://crrev.com/1c628b552ba2f3619518c22f25ef983e81490831
> Cr-Commit-Position: refs/heads/master@{#350138}

TBR=bauerb@chromium.org,knn@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=518830

[dcheng, 2015-09-23 23:28:35]

Created Revert of ChildAccountService[Java] delegates everything to native side.

[dcheng, 2015-09-23 23:31:05]

The CQ bit was unchecked by dcheng@chromium.org