Add missing "chromeos" dependency to ui/base deps

Add missing "chromeos" dependency to ui/base deps

This dependency is already present in the GYP build.

BUG=445627
TEST=gn gen out_gn_ozone --args='os="chromeos" use_ozone=true is_component_build=true' &&
  ninja -C out_gn_ozone chrome ozone_unittests (along with other needed changes)

Committed: https://crrev.com/4202342b03f5a41192f6b25bf1a9b371d266c6b5
Cr-Commit-Position: refs/heads/master@{#314473}

[spang, 2015-02-04 01:22:45]

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

[Nico, 2015-02-04 01:24:12]

lgtm

[spang, 2015-02-04 01:27:54]

The CQ bit was checked by spang@chromium.org

[commit-bot: I haz the power, 2015-02-04 01:28:53]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/874293006/1

[commit-bot: I haz the power, 2015-02-04 02:05:01]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-02-04 02:06:27]

Patchset 1 (id:??) landed as
https://crrev.com/4202342b03f5a41192f6b25bf1a9b371d266c6b5
Cr-Commit-Position: refs/heads/master@{#314473}