trunks: added implementation for authorization_session

BUG=chromium:415999
TEST=unit and manual
CQ-DEPEND=CL:237326
Change-Id: I0c67241241d1e75b0556daf5107516e2be3f9def
Reviewed-on: https://chromium-review.googlesource.com/229920
Reviewed-by: Utkarsh Sanghi <usanghi@chromium.org>
Commit-Queue: Utkarsh Sanghi <usanghi@chromium.org>
Tested-by: Utkarsh Sanghi <usanghi@chromium.org>
5 files changed