Use permission_broker's OpenPath method to open HID devices.

Use permission_broker's OpenPath method to open HID devices.

This new method allows Chrome to open device nodes without having to
chmod them to a group of which Chrome is a member and allows the
permission broker to set opens on the file descriptor before passing it
to Chrome. This is a win for security and future extensibility.

BUG=None

Committed: https://crrev.com/e6aead1fa5623666c4e5cd78ce17e1935ee769b1
Cr-Commit-Position: refs/heads/master@{#338367}

[Reilly Grant (use Gerrit), 2015-07-10 20:17:32]

reillyg@chromium.org changed reviewers:
+ rpaquay@chromium.org

[rpaquay, 2015-07-10 21:27:14]

lgtm

[Reilly Grant (use Gerrit), 2015-07-10 21:28:12]

The CQ bit was checked by reillyg@chromium.org

[commit-bot: I haz the power, 2015-07-10 21:30:09]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1233753002/1

[commit-bot: I haz the power, 2015-07-10 21:36:22]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-07-10 21:37:37]

Patchset 1 (id:??) landed as
https://crrev.com/e6aead1fa5623666c4e5cd78ce17e1935ee769b1
Cr-Commit-Position: refs/heads/master@{#338367}