MacViews: Fix app_list_unittests for mouseover change in r311143

MacViews: Fix app_list_unittests for mouseover change in r311143

Compile of app_list_unittests on toolkit-views enabled Mac regressed in
r311143 because it accessed aura::Window and there is no Aura on Mac
yet.

The MouseHoverToHighlight passes on Mac - it just needs to initialize
the event generator differently.

TapGestureToHighlight is disabled on Mac, since there are no touch
events on desktop Mac.

BUG=441573, 445520, 365977
Committed: https://crrev.com/5657bc22e55a5d9bc4e5cb63e9b4b0ffc55ed377
Cr-Commit-Position: refs/heads/master@{#311375}

[tapted, 2015-01-13 06:10:11]

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

[tapted, 2015-01-13 06:22:43]

Hi jack, please take a look

[jackhou1, 2015-01-14 00:34:31]

lgtm

[tapted, 2015-01-14 00:41:05]

The CQ bit was checked by tapted@chromium.org

[commit-bot: I haz the power, 2015-01-14 00:42:14]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/840373003/1

[commit-bot: I haz the power, 2015-01-14 00:47:01]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-01-14 00:49:50]

Patchset 1 (id:??) landed as
https://crrev.com/5657bc22e55a5d9bc4e5cb63e9b4b0ffc55ed377
Cr-Commit-Position: refs/heads/master@{#311375}