linux: Fixes a racy crash by key input at termination.

linux: Fixes a racy crash by key input at termination.

It seems that it's possible that GDK events happen while we're going
to unregister the GDK event handler, and the code must be thread-safe.
(A gpointer |data| in the old code seems pointing to the deleted object.)

This CL removes use of |data| pointer and makes the code thread-safe
without adding any mutex.

BUG=417210
Committed: https://crrev.com/1291d0c2e4435561edcc260aa0b3337dbd583eda
Cr-Commit-Position: refs/heads/master@{#297112}

[Yuki, 2014-09-26 06:01:15]

yukishiino@chromium.org changed reviewers:
+ erg@chromium.org

[Yuki, 2014-09-26 06:01:15]

Could you review this CL?

[Elliot Glaysher, 2014-09-26 17:25:24]

lgtm

[Yuki, 2014-09-27 11:43:27]

The CQ bit was checked by yukishiino@chromium.org

[commit-bot: I haz the power, 2014-09-27 11:44:03]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/610523002/1

[commit-bot: I haz the power, 2014-09-27 11:57:02]

Committed patchset #1 (id:1) as 6a229e2485fbcf4b541ee32209bb76c3d563c6c0

[commit-bot: I haz the power, 2014-09-27 11:57:44]

Patchset 1 (id:??) landed as
https://crrev.com/1291d0c2e4435561edcc260aa0b3337dbd583eda
Cr-Commit-Position: refs/heads/master@{#297112}