Revert of Fix for the font files being maped multiple times (Fontconfig).

Revert of Fix for the font files being maped multiple times (Fontconfig). (patchset #4 id:60001 of https://codereview.chromium.org/697383002/)

BUG=452227
Reason for revert:
Suspected for breaking security_OpenFDs on cros (http://crbug.com/452227):

01/26 13:31:23.658 ERROR|security_O:0147| Found unexpected fds in chrome type=renderer: set(['0500 /usr/share/fonts/croscore/Tinos-Regular.ttf', '0500 /usr/share/fonts/noto/NotoSans-Regular.ttc', '0500 /usr/share/fonts/noto/NotoSans-Bold.ttc'])
01/26 13:31:23.658 DEBUG|security_O:0138| Found pid 8280 for chrome
01/26 13:31:23.660 ERROR|security_O:0147| Found unexpected fds in chrome type=renderer: set(['0500 /usr/share/fonts/noto/NotoSans-Regular.ttc'])

Original issue's description:
> Fix for font files being mmaped multiple times (Fontconfig).
>
> Before this change, when there were a lot of font fallbacks happening on
> the web site, the fallback font was mmaped multiple times, reaching up to
> 200 times in the TC url: http://jsfiddle.net/p5pe81vs/, leading to OOMs
> and crashes for renderer process.
>
> This happens after the change introduced in
> https://codereview.chromium.org/307243002
>
> This CL keeps track of the mmaps for each font ID to avoid any further
> unnecessary IPC requests and mmaps for future requests of the same font
> ID that would result in new FD.
>
> BUG=430021
>
> NOPRESUBMIT=true
> brettw indicates this use of ScopedAllowIO is acceptable.
> Previous code eluded IO checks, this change makes the IO use find-able.
>
> Committed: https://crrev.com/78db5e535ef48c596223fe272572e5679fbb44fd
> Cr-Commit-Position: refs/heads/master@{#313102}

TBR=behdad@google.com,brettw@chromium.org,bungeman@chromium.org,derat@chromium.org,dominik.rottsches@intel.com,eae@chromium.org,jln@chromium.org,reed@chromium.org,jam@chromium.org,jochen@chromium.org,kolczyk@opera.com
NOPRESUBMIT=true
NOTREECHECKS=true
BUG=430021
Committed: https://crrev.com/2af12ff9d1f88963c3a3ff443002be21c78d74b3
Cr-Commit-Position: refs/heads/master@{#313171}

[tbarzic, 2015-01-26 22:52:17]

Created Revert of Fix for the font files being maped multiple times
(Fontconfig).

[tbarzic, 2015-01-26 22:53:24]

The CQ bit was checked by tbarzic@chromium.org

[Daniel Erat, 2015-01-26 22:53:40]

lgtm

[commit-bot: I haz the power, 2015-01-26 22:54:23]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/873213003/1

[commit-bot: I haz the power, 2015-01-26 23:42:50]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-01-26 23:44:06]

Patchset 1 (id:??) landed as
https://crrev.com/2af12ff9d1f88963c3a3ff443002be21c78d74b3
Cr-Commit-Position: refs/heads/master@{#313171}