Revert of Pre-cache downloads directory path in PathUtils.

Revert of Pre-cache downloads directory path in PathUtils. (patchset #1 id:1 of https://codereview.chromium.org/1281273003/ )

Reason for revert:
Revert because it breaks new beta. See
https://code.google.com/p/chromium/issues/detail?id=528377

Original issue's description:
> Pre-cache downloads directory path in PathUtils.
>
> When Chrome tabs are swiped away and user starts Chrome again,
> their default downloads directory is requested. This causes a
> StrictMode policy violation since it results in a ~60ms disk
> read. Thus by adding this call to the initial AsyncTask we
> save that time when the directory is requested by native.
>
> This must only be called in the browser process as the sandbox
> processes do not need to make the call nor can they make the
> call(results in NPE).
>
> BUG=508615
>
> Committed: https://crrev.com/4a7568dffab924d3710a68949dca0717bdad3352
> Cr-Commit-Position: refs/heads/master@{#342672}

TBR=yfriedman@google.com,wnwen@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=528377
Committed: https://crrev.com/76a40f98082e9cc63416bf1722eb2dabc65880f5
Cr-Commit-Position: refs/heads/master@{#347518}

[mimee1, 2015-09-04 22:29:37]

Created Revert of Pre-cache downloads directory path in PathUtils.

[commit-bot: I haz the power, 2015-09-04 22:30:09]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1328043002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1328043002/1

[commit-bot: I haz the power, 2015-09-04 22:30:10]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-09-04 22:30:10]

No L-G-T-M from a valid reviewer yet. Only full committers are accepted.
Even if an L-G-T-M may have been provided, it was from a non-committer,
_not_ a full super star committer.
See http://www.chromium.org/getting-involved/become-a-committer
Note that this has nothing to do with OWNERS files.

[acleung1, 2015-09-04 22:52:58]

acleung@chromium.org changed reviewers:
+ acleung@chromium.org

[acleung1, 2015-09-04 22:53:12]

The CQ bit was checked by acleung@chromium.org

[acleung1, 2015-09-04 22:53:12]

lgtm

[commit-bot: I haz the power, 2015-09-04 22:53:33]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1328043002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1328043002/1

[commit-bot: I haz the power, 2015-09-04 22:54:21]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-09-04 22:55:31]

Patchset 1 (id:??) landed as
https://crrev.com/76a40f98082e9cc63416bf1722eb2dabc65880f5
Cr-Commit-Position: refs/heads/master@{#347518}