ozone: Add UiThreadGpu for applications that do UI thread GL

ozone: Add UiThreadGpu for applications that do UI thread GL

The demo does GL on the main thread, which broken since we now depend on
GpuPlatformSupport(Host). Let's deliver these messages directly via a
helper class for those applications.

BUG=409978
TEST=ozone_demo --ozone-platform=gbm on link_freon
NOTRY=true

Committed: https://crrev.com/aa2a372038d7faf53f0f98194fdac467b56580de
Cr-Commit-Position: refs/heads/master@{#293075}

[spang, 2014-09-02 19:58:01]

spang@chromium.org changed reviewers:
+ alexst@chromium.org, dnicoara@chromium.org

[dnicoara, 2014-09-02 20:04:09]

lgtm

[alexst (slow to review), 2014-09-02 20:08:52]

lgtm

[spang, 2014-09-03 02:36:02]

The CQ bit was checked by spang@chromium.org

[commit-bot: I haz the power, 2014-09-03 02:38:28]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/spang@chromium.org/533803003/40001

[commit-bot: I haz the power, 2014-09-03 05:17:47]

Committed patchset #3 (id:40001) as 193df099fb63199978f802bc31c91a03532315c9

[commit-bot: I haz the power, 2014-09-10 03:23:41]

Patchset 3 (id:??) landed as
https://crrev.com/aa2a372038d7faf53f0f98194fdac467b56580de
Cr-Commit-Position: refs/heads/master@{#293075}