Revert of Base: Make FileProxy automaticaly close the file on a worker thread.

Revert of Base: Make FileProxy automaticaly close the file on a worker thread. (https://codereview.chromium.org/231703002/)

Reason for revert:
Triggering AssertIOAllowed on a handful of Blink LayoutTests.

Original issue's description:
> Base: Make FileProxy automaticaly close the file on a worker thread.
> 
> This CL removes the restriction that callers should call Close before
> deleting the object if they want to make sure the file is not closed
> on the current thread.
> 
> BUG=322664
> TEST=base_unittests
> 
> Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=263675

TBR=willchan@chromium.org,rvargas@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=322664
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=263758

[leviw_travelin_and_unemployed, 2014-04-15 00:42:47]

Created Revert of Base: Make FileProxy automaticaly close the file on a worker
thread.

[commit-bot: I haz the power, 2014-04-15 00:43:27]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/leviw@chromium.org/238383003/1

[commit-bot: I haz the power, 2014-04-15 00:47:55]

Change committed as 263758

[rvargas (doing something else), 2014-04-15 15:20:17]

On 2014/04/15 00:47:55, I haz the power (commit-bot) wrote:
> Change committed as 263758

Do you have a call stack or link to a bot?

[leviw_travelin_and_unemployed, 2014-04-15 16:01:57]

See some crashes in the results here:
http://test-results.appspot.com/dashboards/flakiness_dashboard.html#group=%40...