Hook up GN official build and branding.

Hook up GN official build and branding.

This passes the official build and branding flags to the GN build. Currently, this is used to hook up the proper sysroot for compiling on Linux for official builds. The 32-bit branded build does not compile currently due to pending pkgconfig issues.

Fix a bug where assertions in the build config would not get reported properly. This was because I forgot to actually throw the error at the toplevel.

BUG=
R=piman@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=240918

[piman, 2013-12-14 01:43:06]

lgtm

[commit-bot: I haz the power, 2013-12-14 04:19:12]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/brettw@chromium.org/115643002/10001

[commit-bot: I haz the power, 2013-12-14 05:21:52]

Retried try job too often on linux_rel for step(s) check_deps
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=linux_rel&...

[commit-bot: I haz the power, 2013-12-14 20:01:55]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/brettw@chromium.org/115643002/10001

[commit-bot: I haz the power, 2013-12-14 20:44:58]

Retried try job too often on linux_rel for step(s) browser_tests
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=linux_rel&...

[brettw, 2013-12-16 17:59:27]

Committed patchset #2 manually as r240918 (presubmit successful).

[Nico, 2014-01-01 04:04:24]

https://codereview.chromium.org/115643002/diff/10001/build/config/linux/sysro...
File build/config/linux/sysroot.gni (right):

https://codereview.chromium.org/115643002/diff/10001/build/config/linux/sysro...
build/config/linux/sysroot.gni:23: # TODO(brettw) this needs to be configurable
somehow.
In addition to this (which means the tutorial currently doesn't work on OS X),
it's strange that this is in build/config/linux.

(gyp's logic for autodetecting the sdk is in build/mac/find_sdk.py  and
build/common.gypi calling out to that script)

[brettw, 2014-01-02 03:53:17]

https://codereview.chromium.org/115643002/diff/10001/build/config/linux/sysro...
File build/config/linux/sysroot.gni (right):

https://codereview.chromium.org/115643002/diff/10001/build/config/linux/sysro...
build/config/linux/sysroot.gni:23: # TODO(brettw) this needs to be configurable
somehow.
Good point, I'll move this.