Add linux_arm_compile to the CQ as a 10 percent experiment

Add linux_arm_compile to the CQ as a 10 percent experiment

The goal is to get this config into the CQ so it can
then become a tree closer on the main waterfall.  The
bot has been pretty reliable, and it only compiles
without running any tests so is relatively quick:
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_arm_compile

BUG=384104
Committed: https://crrev.com/e656ade155c82fd857fc02d90f3811acf3d22c54
Cr-Commit-Position: refs/heads/master@{#318076}

[Sam Clegg, 2015-02-25 00:02:27]

sbc@chromium.org changed reviewers:
+ sergeyberezin@chromium.org

[Sam Clegg, 2015-02-25 00:03:37]

Should I make it a 50% experiment perhaps? Or run it at 10 for while then move
up?

[Sergey Berezin, 2015-02-25 01:27:23]

On 2015/02/25 00:03:37, Sam Clegg wrote:
> Should I make it a 50% experiment perhaps? Or run it at 10 for while then move
> up?

LGTM as is for 10%, but note that the bot is part of a small 12-slave pool, and
it takes 40min to 1 hour to run (which is too slow for CQ, btw), and the pool
will not handle much more than 10% load. It's possible, of course, that it'll
run much faster with a "warm" checkout.

The bot needs to be moved to a bigger pool before increasing the load, and
possibly sped up. In particular, it should use analyze.py to skip compilation
when possible (further reducing the load).

+CQ team for more info (I'm no longer on CQ).

[Sergey Berezin, 2015-02-25 01:30:33]

Another note: the recipe for the bot currently uses chromium_trybot_legacy, and
I bet CQ folks will ask for upgrading it to chromium_trybot + making it based on
the waterfall bot (the "ng" style) before it's ready for production.

[Sam Clegg, 2015-02-25 17:25:59]

The CQ bit was checked by sbc@chromium.org

[commit-bot: I haz the power, 2015-02-25 17:27:10]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/956743002/20001

[commit-bot: I haz the power, 2015-02-25 18:03:38]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-02-25 18:04:17]

Patchset 2 (id:??) landed as
https://crrev.com/e656ade155c82fd857fc02d90f3811acf3d22c54
Cr-Commit-Position: refs/heads/master@{#318076}