clang/win: Make everything work in a GN build.

clang/win: Make everything work in a GN build.

Do this by removing the default_warnings config, moving the flags in there to a
variable, and use it in both the chromium_code and no_chromium_code configs.

If a target does

    configs -= [ "//build/config/compiler:chromium_code" ]
    configs += [ "//build/config/compiler:no_chromium_code" ]

this would add no_chromium_code to the end of configs previously, and the
-Wno-foo flags in default_warnings would be passed before the /W3 flag in
no_chromium_code (and /W3 would then override some of the -Wno-foo flags).
By moving the flags into no_chromium_code, they're guaranteed to appear
after /W3 (and after -Wall on POSIX).

See also thread "configs and warning cflag ordering" on gn-dev:
https://groups.google.com/a/chromium.org/forum/#!topic/gn-dev/qkqdlwtcQW4

In a similar vein, move a -Wno-foo flag in skia/BUILD.gn into a config, to make sure
it appears at the end of the compile command.

While here, also remove /wd4267 from skia's BUILD.gn, it's already passed globally
(this part doesn't change behavior).

(clang-cl working with gn also needs an ffmpeg roll to pick up
https://chromium.googlesource.com/chromium/third_party/ffmpeg/+/5eb7926d25142b65d77be3706ff8bd8116a9d150
This is blocked on http://crbug.com/496975)

BUG=491209
CQ_EXTRA_TRYBOTS=tryserver.chromium.linux:android_chromium_gn_compile_dbg,android_chromium_gn_compile_rel;tryserver.chromium.win:win8_chromium_gn_rel,win8_chromium_gn_dbg;tryserver.chromium.mac:mac_chromium_gn_rel,mac_chromium_gn_dbg

Committed: https://crrev.com/0bfa8a8a759697b140ef2a18f058513ec8485a57
Cr-Commit-Position: refs/heads/master@{#333380}

[Nico, 2015-06-08 19:44:30]

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

[Nico, 2015-06-08 19:48:50]

Please hold off for a bit, this doesn't seem to build yet

[Nico, 2015-06-08 19:57:41]

Ok, please take a look at patch set 6.

[brettw, 2015-06-08 20:53:03]

lgtm

[Nico, 2015-06-08 20:57:56]

The CQ bit was checked by thakis@chromium.org

[commit-bot: I haz the power, 2015-06-08 20:59:37]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1151303006/100001

[commit-bot: I haz the power, 2015-06-08 21:19:15]

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

[commit-bot: I haz the power, 2015-06-08 21:19:16]

Try jobs failed on following builders:
  win8_chromium_gn_rel on tryserver.chromium.win (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.win/builders/win8_chromium_gn_...)

[Nico, 2015-06-08 21:32:45]

Heh, that's broken on the main waterfall too:
http://build.chromium.org/p/chromium.win/builders/Win%20x64%20GN/builds/2512/...
:-/

On Mon, Jun 8, 2015 at 2:19 PM, 'commit-bot: I haz the power' via
codereview.chromium.org <reply@chromiumcodereview-hr.appspotmail.com> wrote:

> Try jobs failed on following builders:
>   win8_chromium_gn_rel on tryserver.chromium.win (JOB_FAILED,
>
>
http://build.chromium.org/p/tryserver.chromium.win/builders/win8_chromium_gn_...
> )
>
> https://codereview.chromium.org/1151303006/
>

To unsubscribe from this group and stop receiving emails from it, send an email
to chromium-reviews+unsubscribe@chromium.org.

[Nico, 2015-06-08 21:52:16]

The CQ bit was checked by thakis@chromium.org

[commit-bot: I haz the power, 2015-06-08 21:53:35]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1151303006/100001

[commit-bot: I haz the power, 2015-06-08 23:14:28]

Committed patchset #6 (id:100001)

[commit-bot: I haz the power, 2015-06-08 23:15:34]

Patchset 6 (id:??) landed as
https://crrev.com/0bfa8a8a759697b140ef2a18f058513ec8485a57
Cr-Commit-Position: refs/heads/master@{#333380}