Update build args for containerized engine to target linux.

Update gn args instructions for engine inside a docker container.

Blimp uses target_os=chromeos to avoid dependencies (e.g. X11) that are the default on linux, but will be unavailable in a docker container.

However this causes a host of other changes to the resulting binary that are not desired (e.g. crash reporting flow).

This change uses target_os='linux' with the unsupported dependencies turned off.  It will work within a docker container without the unwanted binary changes.

BUG=589166, 590816
Committed: https://crrev.com/fceb956ec7d991db287f963e3a5368422de58b02
Cr-Commit-Position: refs/heads/master@{#378794}

[Jess, 2016-02-29 18:36:42]

Description was changed from

==========
New gn args for engine inside a docker container.

Now uses target_os='linux' with unsupported dependencies turned off.

BUG=
==========

to

==========
New gn args instructions for engine inside a docker container.

Now uses target_os='linux' with unsupported dependencies turned off.

BUG=
==========

[Jess, 2016-02-29 18:36:42]

jessicag@chromium.org changed reviewers:
+ maniscalco@chromium.org, nyquist@chromium.org

[Jess, 2016-02-29 18:38:11]

I've tested these arguments in a local docker container.

[maniscalco, 2016-02-29 18:48:30]

Great!  Glad to see it was simple.

Two things, otherwise LGTM.

1. In general, the first line of a commit message should be an imperative
statement.  For example:

"Update build args for containerized engine to target linux"

2. Do we already have a crbug to track this work?  If not, lease create one and
link it in the commit notes (BUG=).

[Jess, 2016-02-29 19:02:53]

Description was changed from

==========
New gn args instructions for engine inside a docker container.

Now uses target_os='linux' with unsupported dependencies turned off.

BUG=
==========

to

==========
Update gn args instructions for engine inside a docker container.

Now uses target_os='linux' with unsupported dependencies turned off.

BUG=
==========

[Jess, 2016-02-29 19:10:18]

Description was changed from

==========
Update gn args instructions for engine inside a docker container.

Now uses target_os='linux' with unsupported dependencies turned off.

BUG=
==========

to

==========
Update gn args instructions for engine inside a docker container.

Now uses target_os='linux' with unsupported dependencies turned off.

BUG=590816
==========

[Jess, 2016-02-29 19:15:32]

Done & done.

Let me know your thoughts on
https://bugs.chromium.org/p/chromium/issues/detail?id=590816

My prior crbugs have been for stability triage only, so let me know if something
is out of norm.

[Jess, 2016-02-29 21:13:28]

Description was changed from

==========
Update gn args instructions for engine inside a docker container.

Now uses target_os='linux' with unsupported dependencies turned off.

BUG=590816
==========

to

==========
Update gn args instructions for engine inside a docker container.

Now uses target_os='linux' with unsupported dependencies turned off.

BUG=589166
==========

[Jess, 2016-02-29 21:25:34]

Description was changed from

==========
Update gn args instructions for engine inside a docker container.

Now uses target_os='linux' with unsupported dependencies turned off.

BUG=589166
==========

to

==========
Update gn args instructions for engine inside a docker container.

Now uses target_os='linux' with unsupported dependencies turned off.

BUG=589166, 590816
==========

[nyquist, 2016-03-02 08:30:24]

Did this somehow change the output of the manifest-generation script, by the
way?

Regardless, this lgtm! I like this a lot!

One tiny note about the CL description, by the way: In addition to your already
awesome single-line description, could you see if you could answer these
questions:
- Before this CL, what was going on?
- Why was that bad?
- How does this CL make it better?

Personally I try to have one short paragraph for each of those questions for
almost all my CLs, and I find that it helps a lot for reviewers and for looking
back at old CLs.

From reading your bug description, you've more or less answered exactly those
questions already there, which is great! But I find it even more awesome if I
don't have to first parse a bug number for a CL description, then open the bug,
then skim through it to find the information, when it could be put in the commit
description as well.

Anyway, like I said, this looks great. Thanks for doing this!

[Jess, 2016-03-02 18:17:20]

Description was changed from

==========
Update gn args instructions for engine inside a docker container.

Now uses target_os='linux' with unsupported dependencies turned off.

BUG=589166, 590816
==========

to

==========
Update gn args instructions for engine inside a docker container.

Blimp uses target_os=chromeos to avoid dependencies (e.g. X11) that are the
default on linux, but will be unavailable in a docker container.

However this causes a host of other changes to the resulting binary that are not
desired (e.g. crash reporting flow). 

This change uses target_os='linux' with the unsupported dependencies turned off.
 It will work within a docker container without the unwanted binary changes.

BUG=589166, 590816
==========

[Jess, 2016-03-02 18:24:25]

Thanks for mentioning the manifest-generation script. I ran it and there were no
changes required.

I've expanded to cl description with details from the bug as requested.

[Jess, 2016-03-02 18:24:42]

The CQ bit was checked by jessicag@chromium.org

[commit-bot: I haz the power, 2016-03-02 18:24:55]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1751433002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1751433002/20001

[commit-bot: I haz the power, 2016-03-02 19:16:25]

Description was changed from

==========
Update gn args instructions for engine inside a docker container.

Blimp uses target_os=chromeos to avoid dependencies (e.g. X11) that are the
default on linux, but will be unavailable in a docker container.

However this causes a host of other changes to the resulting binary that are not
desired (e.g. crash reporting flow). 

This change uses target_os='linux' with the unsupported dependencies turned off.
 It will work within a docker container without the unwanted binary changes.

BUG=589166, 590816
==========

to

==========
Update gn args instructions for engine inside a docker container.

Blimp uses target_os=chromeos to avoid dependencies (e.g. X11) that are the
default on linux, but will be unavailable in a docker container.

However this causes a host of other changes to the resulting binary that are not
desired (e.g. crash reporting flow). 

This change uses target_os='linux' with the unsupported dependencies turned off.
 It will work within a docker container without the unwanted binary changes.

BUG=589166, 590816
==========

[commit-bot: I haz the power, 2016-03-02 19:16:26]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2016-03-02 19:17:40]

Description was changed from

==========
Update gn args instructions for engine inside a docker container.

Blimp uses target_os=chromeos to avoid dependencies (e.g. X11) that are the
default on linux, but will be unavailable in a docker container.

However this causes a host of other changes to the resulting binary that are not
desired (e.g. crash reporting flow). 

This change uses target_os='linux' with the unsupported dependencies turned off.
 It will work within a docker container without the unwanted binary changes.

BUG=589166, 590816
==========

to

==========
Update gn args instructions for engine inside a docker container.

Blimp uses target_os=chromeos to avoid dependencies (e.g. X11) that are the
default on linux, but will be unavailable in a docker container.

However this causes a host of other changes to the resulting binary that are not
desired (e.g. crash reporting flow).

This change uses target_os='linux' with the unsupported dependencies turned off.
 It will work within a docker container without the unwanted binary changes.

BUG=589166, 590816

Committed: https://crrev.com/fceb956ec7d991db287f963e3a5368422de58b02
Cr-Commit-Position: refs/heads/master@{#378794}
==========

[commit-bot: I haz the power, 2016-03-02 19:17:41]

Patchset 2 (id:??) landed as
https://crrev.com/fceb956ec7d991db287f963e3a5368422de58b02
Cr-Commit-Position: refs/heads/master@{#378794}