GitLab

Now we are using AttestationClient directly instead of passing through
CryptohomeClient.

BUG=b:158955123
TEST=build ok.

Change-Id: I0275f2ee7515dd907c13f3fdfb0e9ca2da23e3d1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2497391
Commit-Queue: Leo Lai <cylai@google.com>
Reviewed-by: Maksim Ivanov <emaxx@chromium.org>
Cr-Commit-Position: refs/heads/master@{#821277}