gpu/gles2_conform_support: On Chrome OS, don't use system.gyp to pull in GTK+

gpu/gles2_conform_support: On Chrome OS, don't use system.gyp to pull in GTK+

Normally, gles2_conform_support uses system.gyp:gtk to pull in a system copy
of GTK+; however, Chrome OS already installs GTK+, and system.gyp
intentionally does not provide a gtk target on Chrome OS.  Make the
dependencies on system.gyp:gtk conditional on 'chromeos==0'.

BUG=chromium:388784
TEST=Manually build gles2_conform_test on Chrome OS
[email protected], [email protected]

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=280227

[joshtriplett, 2014-06-25 18:36:25]

This change, along with https://codereview.chromium.org/349923010 , fixes the
ability to build the GLES2 conformance test suite on Chrome OS.

[piman, 2014-06-25 20:46:15]

lgtm

[joshtriplett, 2014-06-26 19:05:27]

On 2014/06/25 20:46:15, piman (slow to review) wrote:
> lgtm

Thanks; I don't have commit access yet, so could you please land the patch?

[piman, 2014-06-26 19:46:44]

The CQ bit was checked by [email protected]

[commit-bot: I haz the power, 2014-06-26 19:48:54]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/[email protected]/355453003/1

[commit-bot: I haz the power, 2014-06-26 23:48:16]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  win_chromium_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/win_chromium_rel/buil...)

[commit-bot: I haz the power, 2014-06-27 03:24:37]

Change committed as 280227