MacViews: Use views::TestViewsDelegate in ViewEventTestBase

MacViews: Use views::TestViewsDelegate in ViewEventTestBase

It currently uses ChromeViewsDelegate.

This is a problem for MacViews, because ChromeViewsDelegate only
provides an out-of-process compositor, which isn't available in tests
using ViewEventTestBase.

It's not a problem for Aura, because Aura platforms tend to get their
ContextFactory form aura::Env instead of ViewsDelegate

BUG=403679
Committed: https://crrev.com/10749b7552af6e163ebcf5aa4992a4af03fdba3e
Cr-Commit-Position: refs/heads/master@{#307996}

[tapted, 2014-12-11 07:51:13]

tapted@chromium.org changed reviewers:
+ sky@chromium.org

[tapted, 2014-12-11 07:51:13]

Hi sky, PTAL

[sky, 2014-12-11 15:37:26]

LGTM

[tapted, 2014-12-11 21:32:40]

The CQ bit was checked by tapted@chromium.org

[commit-bot: I haz the power, 2014-12-11 23:13:39]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2014-12-11 23:14:49]

Patchset 2 (id:??) landed as
https://crrev.com/10749b7552af6e163ebcf5aa4992a4af03fdba3e
Cr-Commit-Position: refs/heads/master@{#307996}