Revert of views/mus: Fix showing menu in chrome in mus.

Revert of views/mus: Fix showing menu in chrome in mus. (patchset #2 id:20001 of https://codereview.chromium.org/1460003004/ )

Reason for revert:
Suspected in build failure. see crbug.com/560461

Original issue's description:
> views/mus: Fix showing menu in chrome in mus.
>
> For menus in chrome-in-mus, we attempt to create a Widget hosted in a native
> window. For desktop builds, this means we attempt to host in a HWND or an
> X11 window created by DesktopNativeWidgetAura. But for mus, we want to use
> NativeWidgetMus. To do this, use the native-widget factory first if it's
> available.
>
> BUG=none
>
> Committed: https://crrev.com/2914df72a605451828a05e108c35fe9a1d72c971
> Cr-Commit-Position: refs/heads/master@{#361151}

TBR=sky@chromium.org,jam@chromium.org,sadrul@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=none

Committed: https://crrev.com/25c81fcd8c425e404fc2fe2bbc840c3971867c81
Cr-Commit-Position: refs/heads/master@{#361163}

[beaudoin, 2015-11-23 20:07:28]

Created Revert of views/mus: Fix showing menu in chrome in mus.

[commit-bot: I haz the power, 2015-11-23 20:09:46]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1472873003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1472873003/1

[commit-bot: I haz the power, 2015-11-23 20:15:52]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-11-23 20:17:10]

Patchset 1 (id:??) landed as
https://crrev.com/25c81fcd8c425e404fc2fe2bbc840c3971867c81
Cr-Commit-Position: refs/heads/master@{#361163}

[msw, 2015-11-24 03:28:43]

On 2015/11/23 20:17:10, commit-bot: I haz the power wrote:
> Patchset 1 (id:??) landed as
> https://crrev.com/25c81fcd8c425e404fc2fe2bbc840c3971867c81
> Cr-Commit-Position: refs/heads/master@{#361163}

This revert likely caused the app_tests step to fail on FYI bot "Chromium Mojo
Android":
https://build.chromium.org/p/chromium.mojo/builders/Chromium%20Mojo%20Android...

I filed http://crbug.com/560626: Chromium Mojo Android app_tests step failing