Move some functions in usb_printer_util.cc to an anonymous namespace.

- Some are in usb_printer_util.h but only used in the .cc file.
- One is in usb_printer_util.cc but not defined in the header.

Change-Id: Idd8be1c56685cc0045db337d0365c6b659f2f150
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1578357
Reviewed-by: Sean Kau <skau@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Sean Kau <skau@chromium.org>
Cr-Commit-Position: refs/heads/master@{#653702}
2 files changed