mash: Fix TabletPowerButtonController segfault.

mash: Fix TabletPowerButtonController segfault.

Make TabletPowerButtonController check that
ui::InputDeviceManager exists before trying to register
itself with it.

BUG=682403, 682460
Review-Url: https://codereview.chromium.org/2645523004
Cr-Commit-Position: refs/heads/master@{#444571}
Committed: https://chromium.googlesource.com/chromium/src/+/7493b52a7df965340262a60de51780cbf978dbff

[Daniel Erat, 2017-01-18 23:42:26]

derat@chromium.org changed reviewers:
+ jamescook@chromium.org, warx@chromium.org

[Daniel Erat, 2017-01-18 23:42:26]

james, can you check if this fixes the crash you're seeing? it gets rid of the
segfault for me, but i'm seeing other probably-unrelated rendering brokenness
now.

[Daniel Erat, 2017-01-18 23:42:31]

The CQ bit was checked by derat@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2017-01-18 23:43:10]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[James Cook, 2017-01-19 00:12:02]

It'll be a few minutes before I can test this (in the middle of some crash
reporting stuff) but code LGTM

[commit-bot: I haz the power, 2017-01-19 00:27:57]

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

[commit-bot: I haz the power, 2017-01-19 00:27:58]

Dry run: This issue passed the CQ dry run.

[Daniel Erat, 2017-01-19 00:37:34]

The CQ bit was checked by derat@chromium.org

[commit-bot: I haz the power, 2017-01-19 00:38:05]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-01-19 00:45:47]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1484786254345530, "parent_rev":
"89fba275a0be24ab7a318f92f179f7c9495ccae0", "commit_rev":
"7493b52a7df965340262a60de51780cbf978dbff"}

[commit-bot: I haz the power, 2017-01-19 00:46:19]

Description was changed from

==========
mash: Fix TabletPowerButtonController segfault.

Make TabletPowerButtonController check that
ui::InputDeviceManager exists before trying to register
itself with it.

BUG=682403,682460
==========

to

==========
mash: Fix TabletPowerButtonController segfault.

Make TabletPowerButtonController check that
ui::InputDeviceManager exists before trying to register
itself with it.

BUG=682403,682460

Review-Url: https://codereview.chromium.org/2645523004
Cr-Commit-Position: refs/heads/master@{#444571}
Committed:
https://chromium.googlesource.com/chromium/src/+/7493b52a7df965340262a60de517...
==========

[commit-bot: I haz the power, 2017-01-19 00:46:21]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/7493b52a7df965340262a60de517...

[James Cook, 2017-01-19 01:43:01]

On 2017/01/19 00:46:21, commit-bot: I haz the power wrote:
> Committed patchset #1 (id:1) as
>
https://chromium.googlesource.com/chromium/src/+/7493b52a7df965340262a60de517...

This fixes chrome --mash on device for me with cave (which uses touchview).