Revert of Add support for backgrounding processes on the Mac

Revert of Add support for backgrounding processes on the Mac (patchset #21 id:400001 of https://codereview.chromium.org/989703002/)

Reason for revert:
Speculative; several browser_tests started failing on the Mac 10.9 bots, and this looks like the most likely culprit:

http://build.chromium.org/p/chromium.mac/builders/Mac10.9%20Tests/builds/1929
http://build.chromium.org/p/chromium.mac/builders/Mac10.9%20Tests%20%28dbg%29/builds/6014

Original issue's description:
> Add support for backgrounding processes on the Mac
>
> Added process_mac.cc with implementations of IsProcessBackgrounded() and
> SetProcessBackgrounded().
>
> BUG=460102
TBR=rsesek@chromium.org,gab@chromium.org,asvitkine@chromium.org,avi@chromium.org,kbr@chromium.org,shrike@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=460102
Committed: https://crrev.com/ce6226a7ffe2c1cb7ac5f6cf34b56b8d217686b9
Cr-Commit-Position: refs/heads/master@{#330294}

[Nico, 2015-05-17 01:14:50]

Created Revert of Add support for backgrounding processes on the Mac

[commit-bot: I haz the power, 2015-05-17 01:14:53]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1128183011/1

[commit-bot: I haz the power, 2015-05-17 01:15:43]

Committed patchset #1 (id:1)

[Nico, 2015-05-17 02:31:20]

I'm afraid the revert worked, but bots went green after being consistently red
after the original CL landed :-/

[commit-bot: I haz the power, 2015-05-18 11:32:13]

Patchset 1 (id:??) landed as
https://crrev.com/ce6226a7ffe2c1cb7ac5f6cf34b56b8d217686b9
Cr-Commit-Position: refs/heads/master@{#330294}

[shrike, 2015-05-18 17:29:44]

On 2015/05/17 02:31:20, Nico wrote:
> I'm afraid the revert worked, but bots went green after being consistently red
> after the original CL landed :-/

Hi thakis,

Sorry to hear that my cl caused bots to fail. When I was committing the change
on Friday I had an issue with one of the bots failing a test. The issue is that
some of the tests end up running in a window while Chrome is not the foreground
app, which causes Chrome to background the renderer. As as result, the renderer
process takes more time to complete its work. The test that was failing was a
case of the task not completed in the expected time. This is for 10.9 and higher
only, of course.

I have some questions:

1. Were the bots that failed separate from the ones that run tests during the
check-in process? I don't know that there are such other bots, but if they were
the check-in bots, is it strange that I could check in my changes OK but those
changes caused problems for subsequent committers?

2. How can I see a complete list of the tests that failed, to start trying to
fix the issues?

3. If I am unable to reproduce the problems at check-in time, is it the case
that I will have to address these bugs as best I can, re-commit my cl, and just
see what happens?