Add a UdevEnumerate and a MockUdevEnumerate class.

This CL adds a UdevEnumerate class, which wraps a udev_enumerate C
struct from libudev into a C++ object. It also adds a MockUdevEnumerate
class for unit testing.

BUG=chromium:248824
TEST=Build and run unit tests.

Change-Id: I9624410df74455cfda80fd4f1cadeb8a66b030af
Reviewed-on: https://gerrit.chromium.org/gerrit/58347
Commit-Queue: Ben Chan <benchan@chromium.org>
Tested-by: Ben Chan <benchan@chromium.org>
Reviewed-by: Ben Chan <benchan@chromium.org>
7 files changed