libbrillo: avoid double-binding callbacks and operator() The second bind is a no-op since it doesn't provide any extra arguments, so it's just an unnecessary allocation. Also, it looks like new versions of base::Bind don't like functor objects, so instead of packaging the callback's environment as part of an enclosing object we should just bind in the bits we need as arguments. BUG=b:37434548 TEST=unit tests Change-Id: I4bed9857655958f300bc99fa9508f2e940fc4a9a Reviewed-on: https://chromium-review.googlesource.com/1064880 Commit-Ready: Eric Caruso <[email protected]> Tested-by: Eric Caruso <[email protected]> Reviewed-by: Eric Caruso <[email protected]>