MacViews: Remove redundant virtuals in NativeWidgetMac and co.

MacViews: Remove redundant virtuals in NativeWidgetMac and co.

Strict virtual annotation checks were enabled on Mac in r311365.

This gets toolkit_views for Mac on board.

BUG=417463
Committed: https://crrev.com/d76706534d9d60bab5496bed0ba6299ed0557a11
Cr-Commit-Position: refs/heads/master@{#311528}

[tapted, 2015-01-14 10:23:29]

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

[tapted, 2015-01-14 10:26:56]

Hi sky, please take a look. Just a mechanical change.

[sky, 2015-01-14 16:25:48]

LGTM

[Andre, 2015-01-14 18:46:54]

The CQ bit was checked by andresantoso@chromium.org

[commit-bot: I haz the power, 2015-01-14 18:47:49]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/850843003/20001

[Andre, 2015-01-14 18:48:04]

Queuing commit so I can pick it up.

[commit-bot: I haz the power, 2015-01-14 19:11:12]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-01-14 19:12:26]

Patchset 2 (id:??) landed as
https://crrev.com/d76706534d9d60bab5496bed0ba6299ed0557a11
Cr-Commit-Position: refs/heads/master@{#311528}