ozone: evdev: Drop unmapped key events

ozone: evdev: Drop unmapped key events

In particular BTN_* events for the touchpad should not be dispatched as
keypresses. So just filter any presses that aren't mapped.

BUG=425617
TEST=manual on link_freon, events_unittests

Committed: https://crrev.com/40efb7c79d00766cea2f7e40eb2432765189c6a2
Cr-Commit-Position: refs/heads/master@{#300559}

[spang, 2014-10-21 17:56:52]

spang@chromium.org changed reviewers:
+ kpschoedel@chromium.org

[kpschoedel, 2014-10-21 18:02:17]

lgtm

[spang, 2014-10-21 20:18:18]

The CQ bit was checked by spang@chromium.org

[commit-bot: I haz the power, 2014-10-21 20:19:50]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/668943003/1

[commit-bot: I haz the power, 2014-10-21 22:28:36]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-10-21 22:29:43]

Patchset 1 (id:??) landed as
https://crrev.com/40efb7c79d00766cea2f7e40eb2432765189c6a2
Cr-Commit-Position: refs/heads/master@{#300559}