Always use a UI message loop in the GPU process on Windows.

Always use a UI message loop in the GPU process on Windows.

ANGLE can now create child windows and requires UI messages to be handled.
Because it is not possible to determine if ANGLE will use a child window
when creating surfaces, always use a UI message loop.

BUG=angleproject:961
Committed: https://crrev.com/019d4f33ee70596e34bcf78706c3da4d2d70d4f1
Cr-Commit-Position: refs/heads/master@{#327140}

[Geoff Lang, 2015-04-22 14:34:17]

geofflang@chromium.org changed reviewers:
+ jbauman@chromium.org

[Geoff Lang, 2015-04-22 14:34:28]

@jbauman: PTAL

[jbauman, 2015-04-27 19:53:42]

lgtm

[Geoff Lang, 2015-04-27 19:54:05]

The CQ bit was checked by geofflang@chromium.org

[commit-bot: I haz the power, 2015-04-27 19:54:15]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1097283005/1

[commit-bot: I haz the power, 2015-04-27 21:39:48]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-04-27 21:40:57]

Patchset 1 (id:??) landed as
https://crrev.com/019d4f33ee70596e34bcf78706c3da4d2d70d4f1
Cr-Commit-Position: refs/heads/master@{#327140}