Disable BackgroundRendererProcesses in absence of Finch.

Disable BackgroundRendererProcesses experiment in absence of Finch.

(temporarily in order to get perf waterfall coverage for new session restore tests)

BUG=459600
Committed: https://crrev.com/78011fcdf7c4e17949429bb99fbe6a68ca822b44
Cr-Commit-Position: refs/heads/master@{#324521}

[gab, 2015-04-09 20:19:51]

gab@chromium.org changed reviewers:
+ avi@chromium.org

[gab, 2015-04-09 20:19:52]

Avi PTAL, please CQ if it LGTYs.

Thanks,
Gab

[gab, 2015-04-09 20:20:10]

The CQ bit was checked by gab@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-04-09 20:21:02]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1076033002/1

[Avi (use Gerrit), 2015-04-09 20:24:11]

lgtm

[gab, 2015-04-09 21:06:53]

The CQ bit was unchecked by gab@chromium.org

[gab, 2015-04-09 21:06:59]

The CQ bit was checked by gab@chromium.org

[commit-bot: I haz the power, 2015-04-09 21:07:46]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1076033002/1

[commit-bot: I haz the power, 2015-04-09 22:10:15]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-04-09 22:11:10]

Patchset 1 (id:??) landed as
https://crrev.com/78011fcdf7c4e17949429bb99fbe6a68ca822b44
Cr-Commit-Position: refs/heads/master@{#324521}

[gab, 2015-04-13 12:45:15]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/1083673002/ by gab@chromium.org.

The reason for reverting is: Bring BackgroundRendererProcesses back on trunk --
will give us perf waterfall coverage now (session_restore tests were borked when
this landed so we didn't get the backward effect and are still in the dark
here)....