GN: Enable ui/keyboard:keyboard_unittests, fix up webui targets

GN: Enable ui/keyboard:keyboard_unittests, fix up webui targets

This adds the ui/keyboard:keyboard_unittests target to the GN build and
adds the rest of ui/keyboard/webui/ to the build.  Since the webui bits
are the only parts that need mojo the mojo deps are restricted to that
source set.

R=sky@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=291199

[sky, 2014-08-20 19:09:45]

LGTM

[jamesr, 2014-08-20 20:39:35]

The CQ bit was checked by jamesr@chromium.org

[commit-bot: I haz the power, 2014-08-20 20:41:15]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/jamesr@chromium.org/493833002/1

[commit-bot: I haz the power, 2014-08-20 21:14:21]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  linux_gpu on tryserver.chromium.gpu
(http://build.chromium.org/p/tryserver.chromium.gpu/builders/linux_gpu/builds/...)
  android_dbg_tests_recipe on tryserver.chromium.linux
(http://build.chromium.org/p/tryserver.chromium.linux/builders/android_dbg_tes...)

[commit-bot: I haz the power, 2014-08-20 21:18:24]

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

[commit-bot: I haz the power, 2014-08-20 21:18:25]

Try jobs failed on following builders:
  linux_gpu on tryserver.chromium.gpu
(http://build.chromium.org/p/tryserver.chromium.gpu/builders/linux_gpu/builds/...)

[jamesr, 2014-08-21 20:27:39]

The CQ bit was checked by jamesr@chromium.org

[commit-bot: I haz the power, 2014-08-21 20:31:38]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/jamesr@chromium.org/493833002/1

[commit-bot: I haz the power, 2014-08-21 21:40:55]

Committed patchset #1 (1) as 291199