dbus: Remove dbus::FileDescriptor

BUG=621841
TEST=dbus_unittests
TBR=steel@chromium.org for device/bluetooth/dbus

Review-Url: https://codereview.chromium.org/2337893002
Cr-Original-Commit-Position: refs/heads/master@{#418481}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: dc693afc916d0596e07a0529f162516475c466f3
6 files changed