[Android] Properly validate potentially null InputDevice

[Android] Properly validate potentially null InputDevice

As InputDevice.getDevice() makes no guarantees that the returned device
will be non-null, always validate the return value before using in a
meaningful way as a Gamepad device.

BUG=421168
Committed: https://crrev.com/55f9a7718acb7e0e44d61d6ea55a91179d774ce0
Cr-Commit-Position: refs/heads/master@{#299016}

[jdduke (slow), 2014-10-09 22:14:47]

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

[jdduke (slow), 2014-10-09 22:14:48]

feng@: PTAL, thanks.

[Feng Qian, 2014-10-09 22:26:55]

lgtm

[jdduke (slow), 2014-10-09 22:40:39]

The CQ bit was checked by jdduke@chromium.org

[commit-bot: I haz the power, 2014-10-09 22:42:06]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/644783003/1

[commit-bot: I haz the power, 2014-10-10 00:12:05]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-10-10 00:12:52]

Patchset 1 (id:??) landed as
https://crrev.com/55f9a7718acb7e0e44d61d6ea55a91179d774ce0
Cr-Commit-Position: refs/heads/master@{#299016}