Reduce UsbDeviceInfoPtr storage in //chrome/browser/usb.

As UsbChooserContext stores all device infos available to the device
manager, other storages could be reduced by only keeping guid and
getting the details from UsbChooserContext by GetDeviceInfo() method.

Bug: 699790
Change-Id: I42f19a530fcf030cb896b3b26f218fe019b77e33
Reviewed-on: https://chromium-review.googlesource.com/c/1296313
Commit-Queue: Donna Wu <donna.wu@intel.com>
Reviewed-by: Reilly Grant <reillyg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#604906}
8 files changed