Add WebUsbDeviceManager for permission moving out of device/usb.

This is a preparing CL for USB servicification which introduced
WebUsbDeviceManager and its unit test. As designed, all permission
management for USB devices will be consolidated within //chrome.
Permission checking code in //device/usb will be moved out to this
new class WebUsbDeviceManager.


BUG=699790

Change-Id: I60580152ec31d1962dfdce616bd5b3729a3e60cc
Reviewed-on: https://chromium-review.googlesource.com/1121971
Reviewed-by: Reilly Grant <reillyg@chromium.org>
Commit-Queue: Donna Wu <donna.wu@intel.com>
Cr-Commit-Position: refs/heads/master@{#578508}
10 files changed