[usb_gadget p01] Functions for encoding HID descriptors.

[usb_gadget p01] Functions for encoding HID descriptors.

The hid module defines functions for encoding HID descriptors. These
descriptors are much more free-form than USB descriptors so a different
approach was taken in this module.

BUG=396682
R=rockot@chromium.org,rpaquay@chromium.org,kalman@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=285177

[Ken Rockot(use gerrit already), 2014-07-23 14:45:05]

Just a note while it's in my mind: Please file a meta bug about getting a device
testing framework in place. Feel free to add any number of other dependency bugs
to whatever level of granularity you see fit. Then make sure all these CLs have
at least one bug # associated with them (even if it's just the meta bug)

[Ken Rockot(use gerrit already), 2014-07-23 15:53:30]

lgtm and nice test

[Reilly Grant (use Gerrit), 2014-07-23 18:01:29]

The CQ bit was checked by reillyg@chromium.org

[commit-bot: I haz the power, 2014-07-23 18:02:28]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/reillyg@chromium.org/410813002/60001

[Reilly Grant (use Gerrit), 2014-07-23 18:34:19]

The CQ bit was unchecked by reillyg@chromium.org

[Reilly Grant (use Gerrit), 2014-07-23 23:31:24]

The CQ bit was checked by reillyg@chromium.org

[commit-bot: I haz the power, 2014-07-23 23:33:39]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/reillyg@chromium.org/410813002/60001

[commit-bot: I haz the power, 2014-07-24 10:50:10]

Change committed as 285177