Only send ViewHostMsg_FocusedNodeTouched on Windows

Only send ViewHostMsg_FocusedNodeTouched on Windows

This message is only handled on Windows, and should only be sent on
Windows. The longer term solution will involve removing it entirely,
but in the meantime disable its dispatch on all other platforms.

BUG=420130
Committed: https://crrev.com/45762d28d013c5c985da49eef8d09ca30330012f
Cr-Commit-Position: refs/heads/master@{#298368}

[jdduke (slow), 2014-10-03 17:59:13]

jdduke@chromium.org changed reviewers:
+ jam@chromium.org

[jdduke (slow), 2014-10-03 17:59:13]

jam@: PTAL. I have a follow-up patch (https://codereview.chromium.org/626983002)
that removes the message entirely, but it will likely take some work to get
right.

[jdduke (slow), 2014-10-03 18:01:35]

On 2014/10/03 17:59:13, jdduke wrote:
> jam@: PTAL. I have a follow-up patch
(https://codereview.chromium.org/626983002)
> that removes the message entirely, but it will likely take some work to get
> right.

For now, I could also define guard the message itself to make the Windows
coupling explicit, if you prefer.

[jam, 2014-10-06 23:27:15]

lgtm

[jdduke (slow), 2014-10-07 00:12:17]

The CQ bit was checked by jdduke@chromium.org

[commit-bot: I haz the power, 2014-10-07 00:15:52]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/625013002/1

[commit-bot: I haz the power, 2014-10-07 02:23:13]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-10-07 02:23:14]

Exceeded time limit waiting for builds to trigger.

[jdduke (slow), 2014-10-07 04:03:19]

The CQ bit was checked by jdduke@chromium.org

[commit-bot: I haz the power, 2014-10-07 04:05:20]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/625013002/1

[commit-bot: I haz the power, 2014-10-07 04:19:16]

Committed patchset #1 (id:1) as 7a09416e1338272f8f171aa937147ccb729c13c0

[commit-bot: I haz the power, 2014-10-07 04:20:38]

Patchset 1 (id:??) landed as
https://crrev.com/45762d28d013c5c985da49eef8d09ca30330012f
Cr-Commit-Position: refs/heads/master@{#298368}