Convert views X11 UnhandledKeyboardEventHandler to other Linux platforms

Convert views X11 UnhandledKeyboardEventHandler to other Linux platforms

We have two Linux platforms supported under Aura: Ozone and X11. The files
being changed on this CL don't touch any X11 specific code, so they can used by Ozone as well.

Linux GTK+ takes another path, not using views, so this change doesn't affect that.

BUG=295089
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=230803

[sky, 2013-10-23 14:49:55]

How was this being handled on win-aura before? By that I mean presumably we
didn't need this on win-aura before, so why do we need it now?

[vignatti (out of this project), 2013-10-23 15:19:24]

On 2013/10/23 14:49:55, sky wrote:
> How was this being handled on win-aura before? By that I mean presumably we
> didn't need this on win-aura before, so why do we need it now?

I'm sorry but I'm not really sure how Win and its different configurations
(Aura, non-Aura, Ash?) works. Do you think is better to name it to _linux.cc so
we make sure that the code won't make any changes to the Win platforms?

[sky, 2013-10-23 20:08:32]

Yes.

[vignatti (out of this project), 2013-10-24 08:08:23]

On 2013/10/23 20:08:32, sky wrote:
> Yes.

alright, thanks. PTAL.

[sky, 2013-10-24 15:42:24]

LGTM

[commit-bot: I haz the power, 2013-10-24 16:13:05]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/tiago.vignatti@intel.com/34573002/70001

[commit-bot: I haz the power, 2013-10-24 20:43:30]

Change committed as 230803