libbrillo: add location to FileDescriptorWatcher constructor

The constructor for this upstream takes a Location object. We've
added this as a transparent wrapper around the current nullary
constructor so we can move to the new API without changing the
client code.

BUG=b:37434548
TEST=unit tests

Change-Id: I3889a74e8561a9e5c77a05bc938745cac2d01661
Reviewed-on: https://chromium-review.googlesource.com/905510
Commit-Ready: Eric Caruso <ejcaruso@chromium.org>
Tested-by: Eric Caruso <ejcaruso@chromium.org>
Reviewed-by: Dan Erat <derat@chromium.org>
2 files changed