third_party/iaccessible2: Fix BUILD.gn for a third-party library.

third_party/iaccessible2: Fix BUILD.gn for a third-party library.

We want to enable a warning that fires on unused variables
(-Wno-unused-variable). It's currently globally disabled. Since it
fires on many third-party libraries, we want to disable it for
no_chromium_code instead.

iaccessible2 is a third-party library but currently uses the config
"chromium_code". Remove config "chromium_code" and
add config "no_chromium_code" so that iaccessible2 gets
-Wno-unused-variable.

BUG=506486, 505319
Committed: https://crrev.com/63b0670cbe0ed69c852552ac1d4a5d02505a4b89
Cr-Commit-Position: refs/heads/master@{#337416}

[Matt Giuca, 2015-07-02 08:07:09]

mgiuca@chromium.org changed reviewers:
+ brettw@chromium.org

[Nico, 2015-07-02 15:08:38]

thakis@chromium.org changed reviewers:
+ thakis@chromium.org

[Nico, 2015-07-02 15:08:39]

lgtm

[Nico, 2015-07-02 17:22:34]

The CQ bit was checked by thakis@chromium.org

[commit-bot: I haz the power, 2015-07-02 17:23:07]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1214163009/1

[commit-bot: I haz the power, 2015-07-02 17:29:19]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-07-02 17:29:20]

Try jobs failed on following builders:
  chromium_presubmit on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/chromium_presub...)

[brettw, 2015-07-03 23:32:25]

This doesn't say why we would do this. It's not a requirement that third_party
code be compiled without warnings. If you're having a warning, please explain
what the issue is.

[Nico, 2015-07-03 23:47:20]

On 2015/07/03 23:32:25, brettw wrote:
> This doesn't say why we would do this. It's not a requirement that third_party
> code be compiled without warnings.

All code must build without warnings, for we build with /WX / -Werror. I guess
you meant "it's not a requirement that third-party code builds with
no_chromium_code if it can build with chromium_code" (?)

> If you're having a warning, please explain
> what the issue is.

I edited the CL description to hopefully explain this better.
http://code.google.com/p/chromium/issues/detail?id=505319#c14 from the linked
BUG= also talks about this

[Matt Giuca, 2015-07-06 00:06:48]

I think the discussion about the specific warning (-Wno-unused-variable) is
besides the point here (and I deliberately split this CL off from my main patch,
and didn't mention the warning in the Cl description, because this change is not
specific to that warning).

The problem here is that iaccessible2 is being compiled with the "chromium_code"
config, whereas all the other third-party libraries that aren't maintained by
the Chromium team are compiled with "no_chromium_code". This config abstracts
over any policy decisions that the team makes in the future that differ between
Chromium and non-Chromium code (such as which warnings to enable), so it's
important to build the library with the correct config.

[brettw, 2015-07-06 17:00:22]

LGTM with new description. There's no policy I'm aware of that says third_party
code must be compiled with no_chromium_code if it compiles without warnings
using our full warning set. I just don't want us running around disabling
warnings for no reason.

[Nico, 2015-07-06 17:01:20]

The CQ bit was checked by thakis@chromium.org

[commit-bot: I haz the power, 2015-07-06 17:02:48]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1214163009/1

[commit-bot: I haz the power, 2015-07-06 17:46:15]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-07-06 17:47:08]

Patchset 1 (id:??) landed as
https://crrev.com/63b0670cbe0ed69c852552ac1d4a5d02505a4b89
Cr-Commit-Position: refs/heads/master@{#337416}