Revert of Refactor serving_dirs.

Revert of Refactor serving_dirs. (patchset #7 id:110001 of https://codereview.chromium.org/838253005/)

Reason for revert:
Causing failures on GPU bots

http://build.chromium.org/p/chromium.gpu/builders/Win7%20Release%20%28NVIDIA%29/builds/30080

Original issue's description:
> Refactor serving_dirs with two goals in mind:
>
> 1) Move the serving_dir related logic to one place and add some comments to improve hackability and stability for cloud_storage in telemetry.
>
> 2) Make serving_dirs available for user stories as part of the refactor to remove page_sets.
>
> This is the second part of https://codereview.chromium.org/794493004/, broken out for reviewer ease.
>
> BUG=454531
> BUG=435063
>
> Committed: https://crrev.com/eed596dced7b9e3f7d21c84f695a39b946c62bf2
> Cr-Commit-Position: refs/heads/master@{#320523}

TBR=dtu@chromium.org,sullivan@chromium.org,nednguyen@google.com,chrishenry@google.com,dpranke@chromium.org,aiolos@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=454531
Committed: https://crrev.com/c624e3576c93717d2f670a5df930b9cd1f2625f7
Cr-Commit-Position: refs/heads/master@{#320543}

[vangelis, 2015-03-13 19:06:11]

Created Revert of Refactor serving_dirs.

[commit-bot: I haz the power, 2015-03-13 19:06:21]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1005903004/1

[commit-bot: I haz the power, 2015-03-13 19:07:11]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-03-13 19:07:45]

Patchset 1 (id:??) landed as
https://crrev.com/c624e3576c93717d2f670a5df930b9cd1f2625f7
Cr-Commit-Position: refs/heads/master@{#320543}