Reland: Convert device::UsbConfigDescriptor and friends to structs.

Reland: Convert device::UsbConfigDescriptor and friends to structs.

These classes do not need to be classes and expecially don't need to be
abstract classes as this leads to a complicated implementation and
complicated tests. All USB devices no matter the platform will have the
same descriptor data.

This change follows the model of device::HidDeviceInfo.

Relanding this patch (reverted in crrev.com/294640) after restoring the
call to libusb_free_config_descriptor that was removed during
refactoring and caused failures in the Linux ASan LSan tests.

BUG=

Committed: https://crrev.com/2191196d13b2896f5ba7bc1c6a3371cb86a7e8eb
Cr-Commit-Position: refs/heads/master@{#294734}

[Reilly Grant (use Gerrit), 2014-09-12 22:11:49]

reillyg@chromium.org changed reviewers:
+ dgozman@chromium.org, rockot@chromium.org

[Reilly Grant (use Gerrit), 2014-09-12 22:21:41]

Please take another look. Only one line (in UsbDeviceImpl::GetConfiguration) has
been changed.

[Ken Rockot(use gerrit already), 2014-09-12 22:25:44]

Ah, freeing the descriptor. LGTM

[dgozman, 2014-09-13 04:52:26]

devtools lgtm

[Reilly Grant (use Gerrit), 2014-09-13 04:57:31]

The CQ bit was checked by reillyg@chromium.org

[commit-bot: I haz the power, 2014-09-13 04:58:34]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patchset/568943002/1

[commit-bot: I haz the power, 2014-09-13 05:38:48]

Committed patchset #1 (id:1) as fc91d04379cb97c8776e2ca0db73cf08799cbc7f

[commit-bot: I haz the power, 2014-09-13 05:44:28]

Patchset 1 (id:??) landed as
https://crrev.com/2191196d13b2896f5ba7bc1c6a3371cb86a7e8eb
Cr-Commit-Position: refs/heads/master@{#294734}