media: Support GetStatusForPolicy() in mojo CDM

BUG=709348
TEST=Enable new tests

Change-Id: I3b00ebdaf1e5566b5d180fa52204b0f5f0270625
Reviewed-on: https://chromium-review.googlesource.com/576859
Commit-Queue: Xiaohan Wang <xhwang@chromium.org>
Reviewed-by: John Rummell <jrummell@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#489244}
13 files changed