[usb_gadget p02] Basic USB device implementation.

[usb_gadget p02] Basic USB device implementation.

The gadget.Gadget class implements the basic USB control requests
required by all devices. It handles common operations like changing
the configuration and interface alternatives and fetching descriptors.
The device interfaces with a "chip" which is the USB peripheral
controller that connects the emulated device to a USB host.

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

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=285098

[Ken Rockot(use gerrit already), 2014-07-23 16:02:50]

Rubber stamp lgtm; I have not fully verified the accuracy of the test
expectations, but there appears to be sufficient test coverage.

[Reilly Grant (use Gerrit), 2014-07-23 18:11:16]

On 2014/07/23 16:02:50, Ken Rockot wrote:
> Rubber stamp lgtm; I have not fully verified the accuracy of the test
> expectations, but there appears to be sufficient test coverage.

These first 6 patches have 100% test coverage.

[Reilly Grant (use Gerrit), 2014-07-23 18:11:44]

The CQ bit was checked by reillyg@chromium.org

[commit-bot: I haz the power, 2014-07-23 18:13:48]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/reillyg@chromium.org/407353002/40001

[commit-bot: I haz the power, 2014-07-23 22:13:03]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  win_chromium_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/win_chromium_rel/buil...)

[commit-bot: I haz the power, 2014-07-24 01:04:34]

Change committed as 285098