[automerger skipped] [DO NOT MERGE] Implement key attestation using AndroidKeystore.
am: eb2db286 -s ours
am skip reason: change_id I26de9ea05f515d6643a83d11628490fb49e10743 with SHA1 9af4bc1f is in history
Change-Id: Ib043f2b93d95cb939c1cd2d853e00abfb284e09f