Fix breaking change in It2me Host on Ozone

Fix breaking change in It2me Host on Ozone

Due to a recent threading changes, the Ozone SystemInputInjector must be
created on the UI thread.

This CL moves the creation of the input injector and input controller on
to the browser UI thread.

BUG=458314
Committed: https://crrev.com/9c59eedd7720845a5bc93b6dbc72639305c52ea7
Cr-Commit-Position: refs/heads/master@{#316883}

Committed: https://crrev.com/ab05ec8fc74d598df6cc5114eb9f657be54fca42
Cr-Commit-Position: refs/heads/master@{#316908}

[kelvinp, 2015-02-18 00:56:35]

kelvinp@chromium.org changed reviewers:
+ sergeyu@chromium.org, spang@chromium.org

[kelvinp, 2015-02-18 00:56:45]

PTAL

[spang, 2015-02-18 01:41:53]

lgtm

[Sergey Ulanov, 2015-02-18 01:49:39]

LGTM, but you will probably need to merge this with
https://codereview.chromium.org/929493002/ (in CQ)

[kelvinp, 2015-02-18 17:59:18]

New patchsets have been uploaded after l-g-t-m from
spang@chromium.org,sergeyu@chromium.org

[kelvinp, 2015-02-18 17:59:50]

The CQ bit was checked by kelvinp@chromium.org

[commit-bot: I haz the power, 2015-02-18 18:00:59]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/931393003/20001

[commit-bot: I haz the power, 2015-02-18 20:20:13]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-02-18 20:21:00]

Patchset 2 (id:??) landed as
https://crrev.com/9c59eedd7720845a5bc93b6dbc72639305c52ea7
Cr-Commit-Position: refs/heads/master@{#316883}

[spang, 2015-02-18 21:43:16]

A revert of this CL (patchset #2 id:20001) has been created in
https://codereview.chromium.org/932233002/ by spang@chromium.org.

The reason for reverting is: does not compile.

[kelvinp, 2015-02-18 22:04:12]

The CQ bit was checked by kelvinp@chromium.org

[commit-bot: I haz the power, 2015-02-18 22:04:43]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/931393003/40001

[commit-bot: I haz the power, 2015-02-18 22:57:11]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2015-02-18 23:02:33]

Patchset 3 (id:??) landed as
https://crrev.com/ab05ec8fc74d598df6cc5114eb9f657be54fca42
Cr-Commit-Position: refs/heads/master@{#316908}