chromeos-dbus-bindings: Add support for ObjectManager/Properties When generating D-Bus object proxy classes, add support for D-Bus Object Manager proxy and properties on D-Bus objects. BUG=chromium:431737 TEST=FEATURES=test emerge-link chromeos-dbus-bindings Change-Id: I4d399fc5ed9613e7c51a7b489383fada184e498f Reviewed-on: https://chromium-review.googlesource.com/232532 Tested-by: Alex Vakulenko <[email protected]> Reviewed-by: Vitaly Buka <[email protected]> Commit-Queue: Alex Vakulenko <[email protected]>